I have a dilema..

I am currently 14 weeks pregnant, and I'm planning a really small gender reveal party. My ob said they schedule the anatomy scan for 18 weeks, so I have a little bit of time to plan still.

My problem is, I have no idea how I am going to get my while family together...

My mom works random days doing 12 hours shifts, she is divorced from my dad and engaged to someone else, (which will made it awkward for them and my dad to be in the same room together.), my two nieces (12 and 13) are in foster care, and they come for visits every two weeks. (They have had to miss christmas and thanksgiving with the family, so I want them to be involved in this.) Not to mention, my fiance's family work alot too..

How am I going to announce this without leaving someone out? I want it to be a surprise for me too.. :/