First time missing my period! Help!

After 1 year and 3 months later my husband and I are having a baby! It’s going to be my first, but I don’t know how to do the baby announcement with my stepchildren and parents. The oldest he’s 16 the middle child is she’s 10 and the youngest she’s is 5. Does anyone have any ideas or suggestion of what you may have done as an experienced stepmother and first time mom? I never thought I’d have my first time experience like this and I would like to make it special but with no feelings hurt towards the kids. I made my parents a shirt to announce it to them that they’re going to be grandparents. I’ll be placing it in the box and they would need to open it. I’m just hesitating on what to put for the kids shirts or if I should just give a shirt to my parents. No one knows of me being pregnant only my husband. We both come from small families. I need help because I am not experienced on this.