From @MJistheBOMB who has kindly said I can share this. I've copied and pasted what she has told us.
The Holiday Summation
Lenny are in 4A. Penny asks Leonard if she'd like to help him set up the snacks/food for the gathering of their friends coming over as she sets down veggies and dip on the table. Leonard is putting away the last bits of Christmas decorations and explains to her that he's doing it so that Sheldon doesn't flip out since Christmas time is over. "Sheldon doesn't live here any more..." she argues. "He also doesn't live at Walmart but it didn't stop him from flipping a jack-o-lantern after Halloween." Another take: "He also doesn't live at Walmart but it didn't stop him from (something to do with marshmallow peeps)....and this coming from a man who complains about peeps being hard to find after Easter!" In walk Shamy. Lenny greets them. Sheldon immediately notices mistletoe hanging from the ceiling, "Mistletoe??? Do you manics own a calendar????"
Penny asks them about their trip to Texas. "It's a lonestar state.... That should be a review on yelp, " Sheldon comments. Amy comments that they didn't have a great time. I think all this was said before he noticed the mistletoe actually. "Well, at least you're home." Penny replied with a smile.
The flash backs begin when Sheldon starts telling Lenny the story of what went down in Texas: we see Shamy in a rental car heading towards his mom's house and Sheldon in the passenger seat waking up suddenly and asking how he got there. Back to the present where Amy admits to Lenny she gave Sheldon a special juice so that he would be no trouble while getting to Texas (the plane ride, etc.).
Flashback to Shamy and Mary sitting at the dinner table. Sloppy Joe's are what's for dinner. Mary is finishing up a dinner prayer that ends with, ".....and bless the hands that made the food (something along those lines) and Sheldon comments about that line being self serving. Mary asks them both how things are back at home. Amy starts with, "Howard and Bernadette had the baby!" with a smile. Mary is happy for them and asks, "Will the baby be raised as Jewish or regular?" Amy just stares at her for a moment and Sheldon looks at Amy and says, "Welcome to Texas...." before Amy responds to Mary with, "....they hadn't told us. We have a bit if news ourselves (btw, after Sheldon wakes up in the car, Amy makes the suggestion that they tell Mary they are living together and Sheldon doesn't think it's a good idea really.)....
Sheldon tries to stall by suggesting they start eating the food that "God" made. "Shelly, what's the news?" Mary asks with a smile. He looks at Amy and says, "this is on you...." before turning to his mom and saying, "Amy and I are living together in sin like two New Yorkers." To Sheldon's surprise, Mary is quite happy about it, which obviously makes him question his mother and she replied with, "...by the time you were three, you could name 1,000 different trains and I was convinced that no girl would ever board any of them..."
Also, after Sheldon reveals that to his mom he says something like, "while you scold me, I'm going to get up and get a fork and knife. Joe might by sloppy but Sheldon is not."
Sheldon was offended that his mom basically thought he'd be single forever and stormed out of the room. We later see Amy sitting on the couch with tea with Mary next to her crocheting. "You think I should go talk to him?" "I'm the one he's upset with, I should be the one to talk to him." There's a long pause as Amy looks at Mary, wondering when that would be, "Arrrre you gonna go talk to him now???" Amy asks Mary.
Just then, in walks Sheldon, with a pair of tightie whities on his head and swimming flippers on his feet. Before storming off earlier, he made a comment to Mary that his brother and sister's combined IQ wattage wasn't even enough to power a potato clock, hence his appearance (he's convinced his mom just wanted him to be like them). He sits down in an empty chair and Mary comments to Amy, "You see why I didn't go talk to him?"
At one point, Sheldon and Amy go out, we see them in the rental car and Amy reveals to Sheldon that she had already told Mary that they were living together because she's didn't want it to ever become an issue. Sheldon complains, "My mother thinks I can't find a mate and my mate thinks I can't run my life."
There's a hilarious scene where Sheldon "rebels" and gets one of his ears pierced. Amy is standing by his side as he does it and he screams loudly at the pain. "Then, my mother made me take it out...." he tells Lenny and we see the flashback of Amy pulling the earring out and Sheldon screaming again. "....and then Amy cleaned it with alcohol...." Flashback of Sheldon screaming again."
That pretty much covers Shamys flashback story I think. Some random things related to it: *Leonard made a comment, "keep going, I enjoy other people's pain." *Bernie (after she Howard and the guys come later) makes a comment, "So, you can control it?" After Sheldon makes a comment that he was intentionally being odd with the underwear in his head, etc. *Penny at one point asks Amy, "So how did Sheldon look with the earring?" Amy replied something along the lines of, "like a pirate helping other pirates to stop pirating...." and Sheldon looks at her and nudges her arm with a big smile on his face. It was so cute.
Howardette arrive at 4A with the baby in tow and behind them are their helpers, Raj and Stuart carrying a bunch of baby stuff. LOL. They're happily greeted by Lenny and Shamy. Howard looks under the blanket of the baby in the carrier and comments, "she's sleeping, can't I stick her in your room?" Lenny agree, "of course." "Poppins, Doubtfire, let's go," Howard says to Raj and Stuart who follow him into the bedroom.
Everyone is seated and I can't remember if Lennies flash back story was told first or Howardette's so we'll just go with Lennie's first. They tell everyone that they got into a big fight. Leonard explains that they started watching Luke Cage together, that's their thing and Penny reveals that she watched two episodes without him. Bernie is staring at them both, weirded out that THAT was their big fight and says, "It's like being excited for a Christmas present and getting socks...." Sheldon makes a comment, "What's wrong with socks?" Penny explains to everyone that they they probably fought over something so minor because of the previous Christmas tree fiasco. Flashback: They're in the car, excited about going to get a Christmas tree. They look cute, Penny has reindeer ears on and Leonard has and elf hat and his Spock ears that he's allowing to double as elf ears. Penny sees an ad in the paper, "Oh look! There's this place where you can cut down your own tree!" Next scene is Lenny in the car, dirty, ears falling off their heads, hair messed up, Leonard's glasses are crooked. Obviously the tree cutting didn't go well. Penny makes a comment, "when you swing an axe, you don't let go!" Leonard mentioned his mittens making his hands slippery. "It's 70 degrees, you don't need mittens!!!" Suddenly, the tree y worked so hard to cut down slides down onto the windshield of the car. "There's something on the windshield..." Penny says sarcastically.
Next part of their flashback is them trying to get the damn trees upstairs to 4A. "You need a break?" Penny asks Leonard who has the end of the tree as she leads. "No," he replies. "It's okay to admit you need a break," Penny tells him. "If I need a break I'll tell you!!!," Leonard shouts at her. Next scene is the tree on top of Leonard as he lays on the floor on the second floor or something. "Leonard, there's a tree on you," Penny says sarcastically. Finally, we see them drag the tree through the door of 4A. Leonard makes a comment about decorating it I think and Penny replies, "with gasoline and a match?" before they both tiredly plop themselves down on the couch. That pretty much concludes their flashback.
Howardette's flashback: we at Howardette's house. We hear Hallie crying and Bernie in the room trying to get her to stop, "It's okay, it's okay....I don't know what you want, my boobs are dry, you want money? (In another take she asks, "do you want lasagna?" She is able to calm the baby down and we see her slowly and tiredly walk out in her sweats, hair messed up and she says, "what have we done?" In walks Howard and the guys. They just came home from shopping. "I got super hero baby wipes! They fight crime and tushie!" he says while flipping them in the air. At one point the baby starts crying again. Stuart says, "I'll take this shift." and goes to take care of Hallie. He gets her quiet immediately and it makes her sad and she starts to cry as she sits on the couch. Howard sits down next to her to ask her what's wrong, "nothing, these are happy tears." "Oh, okay...." Howard replies. "They're not happy tears, you big (I forgot what she calls him)." She is sad and thinks the baby doesn't like her. Howard makes a comment maybe Stuart is so successful because Hallie is playing the possum trick (not his wording but the implication is play dead until he goes away I guess). Raj makes a comment that maybe the baby is just a, "jerk". He also made some comments that back home in India, when his baby brother cried, the servants would just take the baby far away so they could hear him, either that or THEY would just leave.
Back to the present, someone (I forgot who) asked Howard how things were/are for him and he mentioned everything was good, besides all the crying. Flashback of him sitting in bed next to a crying Bernie who is still sad thinking her baby doesn't like her. "How can she hate me? I'm like a human milk machine, that's like hating a frozen yogurt machine...,"she cries. Howard is trying his best to comfort her until he loses it and starts crying too.
Finally, the sweetest part of the flashback: Howard opens the door to Hallie's room to check on Bernie with the baby. It's dark and silent. He's whispering, asking where she is. "down here..." she whispers. He slowly walks across the room and uses his cell phone to light his path and there is Bernie laying down in the crib with the baby wrapped up in a blanket sleeping by her side. Howard asks how she could fit in there and I'm forgetting her response. Howard makes a joke about thinking outside of the box since she was basically in one (the crib). He asks her if she wants help out of the crib but she wants to stay with Hallie. He squats down near the crib and asks Bernie, "is it okay if I gets some sleep?" She smiles at him and tells him to go ahead. Howard reaches his hand in towards Bernie and says, "good job, mommy...." She tells him not to make her cry. It was so sweet!!!! That pretty much concludes Howardette's story.
At one point while everyone had been listening to Howardette's story, Sheldon did some googling about the blues that women have after giving birth. He read that being encouraging and complimentary to the new mom is good for her. He pats Bernie on the head and says, "You're doing a good job." "Thank you, Sheldon, I feel better...", Bernie says with a smile.
The tag scene is everyone leaving 4A. They say their goodbyes and Leonard or Penny asked when Howardette return to work, Howard mentions he's in paternity leave and Sheldon chimes in, "a small human reeks havoc (pardon my spelling on those if it's incorrect) on his wife's genitals and he gets time off..." he shakes his head and starts to follow Howard out. Howard turns around, "with pay, sucker! (another take: with pay, homie!)" Everyone is out, then Howard comes back in, "I forgot the baby, I'm new at this...." as he heads back towards Lennies bedroom. THE END. Anything I left out will be a surprise for you all.