@Barry2021,
I mention "biological" because you ALWAYS say that. Nobody here cares, and anyone who has ever read anything you wrote ALREADY KNOWS.
Your BIOLOGICAL daughter asked for help with the party, so help. That doesn't mean deciding what people put on their t-shirts. Who really cares? Why does it matter? For Pete's sake, she's going to be ONE YEAR OLD. Nobody's going to sit around looking at photos of their t-shirts. The photos will go into an album no one will look at, like all photos.
Because you're helping finance this silly party you think you have a say so? That seems very controlling to me. You focus on all the little stuff. Let people write what they want - what harm can it do? "Smallest Auntie of the B'day Girl", "Fattest Uncle of the B'day Girl"... what difference can it possibly make? Why do you have to ruin someone else's good time over such a trivial concern?
And I never suggested you not help her out. How difficult is it to plan a bloody party, anyway? You pick a date, time and location, invite everyone and either ask them all to bring a dish, do the cooking yourself, or have it catered. Even a nitwit could figure that out. And I certainly never questioned why you are involved. Knowing you as I do, you're going to be involved one way or another come hell or high water. Your last two statements are just stupid. Go back to bed and get up on the right side this time.