Physical & Emotional Abuse Support Group
Abuse is a general term for the treatment of someone that causes some kind of harm (to the abused person, to the abusers themselves, or to someone else) that is unlawful or wrongful. No one deserves abuse, period. Abuse can be emotional, physical, or sexual.
You've experienced this before. If your gut instinct is telling you something is off, let your instinct be your guide. Better safe than sorry. Err on the side of caution.
So, how do you deal with the kids? Let their kids come over where you can observe or let your kids go over but not go inside.
I don't know what your relationship is with the mother of the children next door, but if you know her well, explain to her that you have an issue with the lock thing and you don't want your kids to ever lock any of the others inside. Put the onus on you. Say YOU'RE not comfortable with it...
Sorry. Getting carried away. Listen to your gut. I cannot imagine sliding bolts on the outsides of doors.
How many people don't pay attention to their gut reactions and are so sorry later. I'd take Liane's advice and have their kids over to your house for whatever reason. But do listen to your gut reaction about the man - if something feels wrong for your kids it just may be.