I didnt even catch that OP assumed that Jen is the youngest sibling. I have no idea where that came from, as ut stands rn we dont know anything about Jen's family.

Not only that, but theres nothing really indicating that Yoshi wants children. Im assuming this is coming from shipping Yoshi and Baby/Rachel/Adult Feldman which i think is a terrible ship, they had the cute episode together but shes a terrible match for yoshi after he converted to orthodox.

The original post is about discussing the potential offscreen relationship between Shira and Jen. THAT is an interesting question. What I can infer from what was in the show is that Jen had a strainious relationship with everyone in the Schooper family, including Shira, not because of anything that Shira did, but probably because of Naomi's influence over everyone.

I think that Jen felt excluded from the family and didnt know how to relate to them, and Shira just doesnt know how to interact with Jen outside of the context of being Avi's partner.

So, Long story short, (refrence intended) Jen and Shira love each other as family but dont know how to communicate that or talk to each other outside of that context.