DH and I have been together for 7 years, married for 3. He has one DD, she's 24. I have 4 DC, DS is 26 then DDs who are 25, 23, and 20.
My two middle DC have autism, they have always really struggled with socialising and my 23 and 20 year olds live at home, my 25 year old lives 5 minute walk away.
My children and DSD went to school together, she was a year below my eldest DD and a year above my middle DD. My DD's really struggled in school, which wasn't made any better by bullying. DSD was part of the group who did a lot of the bullying (all very sporty, very pretty, middle class girls picking on those who hadn't quite settled, were from lower income families). DSD claims she was never the one doing the bullying but my DDs really struggle when she is around.
My 23 year old really struggles with her autism, she hates it when DSD is here, basically never leaves her room, she is very intimidated by DSD. DD also struggles with routine changes massively and is easily overstimulated.
When DSD is here, she plays music all the time, goes out with her friends and comes back at 2/3 am (she isn't loud but DD is a light sleeper and this will wake DD up and scare her to the point she won't sleep again). My DS also puts on an act when she is here, tries to buddy up with her BF and basically ignores his sisters and says they have to grow up.
Over the years there has been a lot of back and forth. We went out a walk one year and my eldest DD was complaining she was tired and DSD loudly muttered "if you lost weight you wouldn't be tired", she apologised but DD is very insecure so this has stuck with her (DD is a size 14/16 so not exactly big or anything, but DSD is a size 6 and very judgy of any overweight). In an argument about 2 years ago she also shouted at my DD's "You need to grow up, get a real job and stop getting my dad to fund your life". This obviously left sour taste but she again apologised.
DSD has a bit of a superiority complex, she is an Oxbridge grad, now doing her training contract for a law firm in London making crazy money for a grad (she's a couple years behind other her age on average as she did a gap year then a year abroad at uni). She looks down on my family as my DDs didn't go to uni (well DS did and he is the only one she actually gets on with).
On Sunday she and her boyfriend are coming back for a few days, they've only been dating since spring and her dad has met him but none of the rest of us have. As if DSD being home won't cause my girls enough stress, a total stranger in the house will make it 10x worse.
I just know their will be an argument, my DDs will get upset, DS will side with DSD as he thinks it makes him look smart.
DH never has any input, he thinks his DD can do no wrong, total princess in his eyes. He never outright agrees with her but he never tells her to say sorry or calls her out.
AIBU to be absolutely dreading her coming back even if it is just for 3/4 days? I find her so hard to be around at times!