So my sister has form for this kind of thing.
She will go out of her way to offer someone a lift after work but this then holds her back from letting her childcare back by half an hour.
Or volunteer to make ridiculous quantities of buns for a charity bake sale but will "need' friends and family to mind her kids at short notice so she can do this.
She is very much of the attitude that friends and family should "drop everything" to help others, including her when she is in "need", but often she creates these situations where she is scrambling around for childcare because she has committed to something unnecessary, although she will view the act of charity as vital.
I'm all for helping others, absolutely, but AIBU to say that your charitable acts shouldn't be constantly inconveniencing others?