How do I teach my children to respect my co-wife properly?

The most effective way is through your own example: when children see you speak politely about your co-wife, they learn to respect her. Avoid belittling your co-wife in front of the children or making her the butt of sarcasm, because that plants hatred in their young hearts. Teach them to greet her with salam and to be kind when they meet. Explain in suitable language that your co-wife is part of the wider family and deserves respect. If your own feelings are still in turmoil, take care that they do not flow into the children. Children who grow up without inherited grudges have calmer souls. See children & polygyny.