Baby Shower Button

Tinesha • 26 y/o | Single boy mom.
So I made buttons for my shower only for those who aren't guest. I have one that says "mommy to be" I made my mom and sister who lives with me one as well. I'm wondering if my two cousins who has lived with us for years if I should write great cousins or just go with Aunty to be like my sisters. They don't care and are up for it. Should it matter that they aren't actually my sisters?