Kittens feeding on male reproductive organ

I seriously need help with this. I recently got rid of my kittens's mom because even without her, we have 5 cats. 2 babies born in September older baby born in June and to adult cats. They are all males since we got rid of the mother. The problem is that the younger babies have taken to feeding on the one born in June who is now in heat. Yes he is a male, they've been feeding on his penis. And I don't know how to teach them not to. For now I'm keeping them separated from the others but what should I do?

They're not feeding on anything but they are suckling for comfort.  Give them a blanket to suckle instead.  You can dip a corner in some kmr to help them settle down.  It's not necessarily a problem unless they are hurting him.

What do you mean by got rid of her?  Are all of the cats neutered?  Male cats don't go into heat so I'm not sure what you mean by that.  Can you explain?

You should consider neutering these cats if you haven't already.  As they get older they will spray inside your house.

They are suckling for comfort because they miss their mom. Where did mom go? Can she be spayed and returned to you?

Suckling on another's reproductive organs is not healthy for the kittens. The blanket corner soaked in milk is a good alternative.

The male kittens need to be neutered. Do you have a low-cost Humane Society in your area? I had my 3 male kittens neutered at 3 months old at the Humane Society. The younger the better. You may have other low-cost organizations in your area as well.

In the meantime, do keep them separated, but the little guy still needs to play and socialize.

How are your cats doing? Can you answer some of the questions above? It would help with advice.