When they are old enough and if i know the family well

When they are old enough to understand good and bad.

If they are really close and I know the family well

At least when he/she is in the upper primary level.

Too young to stay over... probably age 16 and above

maybe when they show me that they're responsible

If I know the friends parents number it’s ok

If they are close Friend and we know them well

I don't mind his friends sleep over tho...

Only if I know their friends and parents