Family table seating?

I don't think it will be weird at all. After all, they're about to become family anyways I think it'll be a great time for your sister to meet them!

Honestly, you can do whatever you want. Our tables combinations were rather complicated because my husband's parents are divorced, my husband's older brother and sister are estranged from his dad, and my dad is a recovering alcoholic so we had to make sure we didn't sit him with anyone that would be drinking. Our first two tables consisted of most of our bridal party and their spouses. My brother and his wife were the only people in the bridal party that didn't sit at one of the two bridal party tables, but that's because they don't drink so it made sense to sit them with my dad. I have listed below what we did to give you an idea.

Sweetheart table - Just my husband and I

Table 1 - my sister (maid of honor) & her husband, husband's sister (bridesmaid) & her husband, and my husband's younger brother (groomsman) & his wife

Table 2 - friend of the groom (groomswoman), friend of the groom #2 (groomsman) & his wife & child, friend of the groom #3 (best man), and friend of the groom #4 & his wife/my friend (bridesmaid)

Table 3 - my brother (bride's man) & his wife (bridesmaid), my mom & dad, my mom's two friends

Table 4 - husband's mom, husband's aunt & uncle, husband's mom's close friend & her date

Table 6 - husband's older brother & his wife & their four children who were our ring bearer and flower girls

Table 7 - my grandparents (mom's side), my uncle (mom's step-brother), my great aunt & uncle (mom's side), my second cousin & her date, my grandmother (dad's side), and my great uncle (dad's side)

Table 8 - husband's dad & his fiancee, husband's aunt (on his dad's side) & cousin, husband's aunt (on his mom's side, but stayed good friends with his dad after his parents divorced) & two cousins

Other tables - more friends and family

I don't think that would be strange. Your siblings might be more comfortable not being in the spotlight at the head table with toddlers lol.

Thanks for this breakdown!!

Good point! I guess I'm worried that my siblings won't have much time to mingle with my parents but they will have the day before the wedding also (and will still be only a table over).