M.M.
ONce I met a mom and we hit it off I would allow my children to play there.
I have said to my kids that thye will not play in a certain house, call it bad vibes or whatever, the kids always played outside where I could see them.
We started letting them go play at so and so's at 4ish.
My 3rd could actually go over at 3 without me, my neighbor and I joked we should install a hamster tube between the houses the kids were between the houses so often.