After step parent adoption...

First off, congratulations! It sounds like this step parent adoption will be a great thing for your family. I'm so happy that you have a healthy situation now, and that you have had the strength to cut ties with biodad. I know from personal experience that cutting those ties is so, so hard. Secondly,I think your fear is totally valid! Although nothing about their relationship with your little one will change, the relationship their son has with your little one will change, so I can see being hesitant to tell the grandparents. However, in my opinion, it does need to be done. In my experience, the truth always comes out at some point, and to catch them off guard now before or right after it's official would be better than them finding out years down the road. I think it's alright to explain to them that while you're not comfortable with your little one having contact with biodad, the relationship they have with your little one won't be changing just because of the adoption. That you would be happy to have visits still, as long as it's just them and not their son. It makes sense that you're scared, but I think you know it needs to happen. Ripping off the bandaid now will help you feel so much relief down the road. You're tough. If you have the strength to cut ties with biodad and do whatever is best for your child, you have the strength to do this. Do keep us posted and let us know what's going on, and how this community can further support you!