Her Adopted Little Brother Was Pointless?
I get it was a reference to the interracial adoption phase going on in society and headlined by celebrities, probably would've worked as well with a little Asian girl.
Anyway, other than the initial joke where the father hit the wall and demanded to know who told him he was adopted, the little boy served no purpose. He had like 3 lines, and just kinda sat there looking confused during all the family scenes without giving any input, reaction, or even a cheesy one-liner to make it seem like he was actually relevant. Honestly, I can't remember one interaction between him and his 'big sister,' and I don't think Olive even acknowledges the kids existence once during the entire movie!
I mean just one scene with Olive jabbing him, rubbing his head, or yelling at him to get out of her room would've made the kid seem like less of a random accessory. If they were going to add him, they shouldn't have been so... quarter-assed about it? He was added as a running-gag that just never took off running.
Done and dusted.