#82, OP had it right with "my sister and me". If you break down the sentence, which sounds better? "They're fighting over the dog instead of my sister.", "They're fighting over the dog instead of me." OR "They're fighting over the dog instead of I." Proper English rules determine that "my sister and me" is correct, not "my sister and I" despite the fact that to certain ears "my sister and I" sounds slightly less clumsy. I risk sounding like an English snob, but I couldn't let that one slide. In other news, OP, sorry to hear your parents are divorcing. Perhaps it's a blessing in disguise, and in time the family unit will be less problematic because your parents aren't always at each others throats...and fighting over a dog. I think the biggest problem for OP is that the parents are splitting up (and it sounds like it's getting messy), and OP is very hurt by that. Instead of getting consolation and assurance from her folks, she's witness to them fighting over a DOG. It's like OP's feelings (and those of her sister) don't matter much at all, if the parents are squalling over who gets the dog. Divorces are a messy business 9 times out of 10...hopefully everything works out in the end.