Sounds like lots of good advice. Visiting them alone the first time to just talk would be good. However, don't be too hard on them. They may have had a change of heart about the need to connect with their family.
Still, don't allow them to break your rules with your child. They would not do that for you. I agree to try and build a bridge here. They have been controlled by a cruel policy of a mind control group. Of coarse they still own their actions. But wouldn't you prefer to be able to build some kind of loving relationship with them, if possible? Only time will tell if they are sincere.