Healthy children will always present challenges. That is part of their individuation process. A blended family does not automatically produce skilled parents. Birth parents and stepparents all need to learn effective parenting skills. This is a big one.
Prevention is the key.
It is very selfish and immature to go into a marriage with a partner who has children you don't like. However, there is a continuum here. Hopefully, however, he or she will at least have the maturity to show simple kindness and respect to the children. This means handling problems with kindness and firmness, dignity and respect. It means having family meetings so everyone can be involved in stating what their needs are and in brainstorming ways to help everyone get their needs met in ways that are respectful to all concerned.