Help me see the other side I don’t want to be annoyed

So this Father’s Day will be my husband’s very first. I want to do something really fun and special for him and his Dad.

I was texting his mom today and told her that when we’re in town to see them I want to do a fun craft for it. I want to do something that involves her hand print or foot print in some clay and I’m going to do a cool custom paint job around it all. She’s a miracle baby that we never thought we’d have.

So I tell her about it and she tells me it’s a great idea. Then she tells me that she invited our cousin to do it with her kids. They’re all older kids (14, 10, 8). To told my husband that I’m bummed because it was just a sweet little idea I thought for us to do and I don’t see why his cousin can’t find her own. I know I don’t own the rights to the idea but it’s like “hey you figure your own things out”.

I’m not trying to be an ass. I just would like to have something that’s fun and ours.