I would definitely be telling the parents! They probably aren't even aware that the boys are coming over, so they definitely should know.

You obviously really don't need this, with everything else that's going on ATM. I would tell their parents, and make it clear that you don't want them coming over all the time.

I had a similar problem last year with a couple of girls who live close by. They had become friendly with our friend's daughter, who is one of our neighbours. One day they all came by to see our puppy. I took the dog out the front, let them have a pat and that was it. Next thing, I've got these little girls that I hardly know knocking on my door (without the girl that we know) every other day wanting to play with the dog! I think that they are really a bit lonely, but I still didn't think it was on. Their parents have never even laid eyes on us! So I just told them that it wasn't okay, cos their mum and dad don't know us. Eventually they stopped coming around. If it happened again though, I would def. let their parents know.

I hope you can resolve this peacefully!