[Josy]

Eurgh she sounds like a bit of a head buster Caitlin. You should tell her firmly but nicely that you would prefer if stopped bringing up your dads finances with you and your siblings that you feel that's private business of your dads and if he felt the need to discuss it with you then he would.

I don't have any step family at all but a lot of my friends did when we were growing up and they mostly seemed to have problems with them.