To give an example in layman's terms: a mother may tell her child he cannot have cookies from the cookie jar. The father, regardless of his beliefs, cannot tell the child it is okay to have a cookie as that would result in a conflict with the mother. If the father sees the child taking a cookie anyway, he may choose not to say anything.
To illustrate using everyday language: A mother can set boundaries for her child regarding cookies from the jar. The father cannot support this action by saying it is okay because that would contradict the mother's decision. If the father sees the child taking a cookie, he might choose not to intervene.