Need advice!

I’m going for my 8/9 week scan in 2 weeks time and me and my husband are going to tell our parents the day after that they are going to be grandparents.. 🤞🏼so exciting! However, we don’t plan on telling anyone else until the 12 week scan, although we are unsure what to do about our sisters. 1 of my sisters and my OH sister still lives with parents, so we feel it’ll be awkward not to tell them.. but my other sister lives with her husband and her husband is best friends with my OH... and he literally keeps no secrets, so if we tell her she will tell him and then everyone will know. So we are unsure what to do. Do we tell the sisters who live at home without my other one or not?