Dsis has been with her DP over 4 years, so quite a long time (they are not married).
BIL has 2 DC's from a previous relationship who Dsis gets on very well with and spends a lot of time with when BIL has access EOW.
However, Dsis is getting fed up of doing 99% of the childcare on the weekends they are there. BIL is often doing one of his many hobbies or is asleep (he works nights) during the times they are there so even though Dsis works the weekends they are there she has little choice but to do the childcare while she is at home as BIL leaves everything to her, Eg; planning activities for the kids, making their meals, etc.
She is a bit fed up because every time she raises this with BIL he says that since they are a couple, they are basically 'her kids too' and are therefore equally her responsibility as well, so asking her to do all this stuff is completely reasonsable.
I disagree. Obviously she doesn't mind doing some stuff for them Some of the time, that is fine BUT I don't think it should be equally her responsibility, as they are actually his dcs and therefore he should do the majority of the work/childcare while they are there. He physically will not do these things if she is in the house because he assumes she will do it/he is busy etc. I have suggested she come over to my house/goes out for the day/makes other plans on the days they are there to try and get him to do his fair share.
Who is right? Aibu and a mean bitch?