how would you announce?

Me and my SO are currently TTC and I'm trying to think of cute ways to announce to his family that we are pregnant when it finally happens. 
I've got it all planned out how to tell my family but I'm not real sure how to tell all of his. 
I'm especially worried about telling his older sister, she's about 13 years older than us. She's never liked me and I've never really liked her much either. She's been TTC for the past 8 years that I know of and has now been going through <a href="">IVF</a> for the past year or so. 
Any ideas?