My older 2 DS (10 & 8) were invited to sleep over a friends house. I say friend but we don't know them. We have lived here for 4 yrs and have never seen his family. I have seen him waiting at the bus stop but never anyone else. He told us that his Nana takes care of him and that he couldn't answer where his parents are. Should I be concerned? I think we are going to invite his Nana over and get to know them before we consider a sleepover. Are we just being overprotective parents or are we doing the right thing?