Family trouble

So currently my husband and I live across the street from my dad. We take turns cooking dinner for each other, so we see each other daily (and here recently my washer went out so we have been using theirs) Now we try to be separated households as much as possible but at the end of the day we still see everyone almost daily.

Here recently my step-sister (going on 13 on the 21st) tries to over step and parent my one-year old. She also likes to run her mouth towards us when my daughter is getting on her nerves. Like today she tried to claim that my daughter was keeping her mom up, but any other time her mom will come and talk to me about it. (My step sister had also gotten into a lying kick recently)

Im thinking about when we are all at the dinner table today just to talk with everyone at once.