disciplining someone else's kids

Hmm, don't say "or else." Because some parents are SUPER DEFENSIVE about their child and if the kid tells his parents that you said this........then the parents might assume that you're "threatening" their child by saying "or else." They'll defensively wonder, "Or else what? What does Sadzzz plan to do to my kid. He's just a kid."

Take the child to the parent. Or call the parents over to the room. You, the parents, AND THE CHILD..........should be in the same place so that no misunderstandings or assumptions takes place cuz everybody will be present.
Proceed to tell the parents the situation. Explain to the parents that you don't intend to offend them and that you enjoy having them over. But....that you have some rules for kids so that the environment is overall a safe and pleasant one for everyone. Then tell the parents what happened. Tell them that their child hit you. The kid will obviously look guilty and won't be able to hide it well from the parents cuz he'll be put on the spot. And since he'll be in the same room.............he can't fabricate anything. Having 3 adults in the room looking at you.............is a challenging situation for children......and if they're young.......they're likely to not try any chalaki.

Tell the parents. You'd want to know if Heba was misbehaving with an adult so you can nip the problem behavior in the bud. If you don't inform the parents..............then in the future.......he might behave in the same way with OTHER adults (relatives, neighbors, teachers, family friends, etc). His parents have to teach him that he needs to have respect for everyone especially authority figures BESIDES mom and dad. And they can't enforce this concept if they don't know that there's a problem.

I think it's effective. Teachers will often times request that a conference takes place with the parents AND the child present in the same room. That way.........the child hears/sees everything that the teacher has to say. Usually children stay quiet. The parents hear everything. Everything is openly done. AND.........all questions and doubts from the parents and child are answered/cleared by the teacher. This leaves LITTLE ROOM........for the kid to fabricate and lie about things to the parents. Cuz everyone was there.