Do not try to micro manage the other parent’s time and relationship with the children during visitation. It is not up to you, even if you have custody of the children, what they may or may not do when together unless there is an actual danger or harm to the children objectively speaking, not in your opinion. In such a case, call the police or file with the court whichever may be appropriate. You may be the better parent, but that does not make the other parent any less of a parent to be told by you how to and not do things with the children. The other parent does not have to tell you what they will be doing, where they will be going, and so on. And you are not to grill the children about this either at the end of a visit.
Do you tell the other parent everything you do with the children? Everywhere you take the children and when? But that’s different you say? How? Oh, you are the better parent? You are the mother? You are the custodial parent. Sorry, it does NOT work that way.
A factor to be considered when determining a parent’s fitness is that parent’s inclination to encourage regular contact with the noncustodial parent and the children.
A parent’s attempts to alienate the children’s natural affection for the other parent can cause custody to the changed to the other parent.
If the custodial parent “deliberately frustrates, denies or interferes” with the non-custodial parent’s visitation rights, then a custody change is appropriate.
Heavy weight is to be given to the fact that one parent would be much more willing to encourage undisturbed contact with the noncustodial parent than would the other parent.
Any interference by a parent with the other parent’s right to a relationship with the children is an act so inconsistent with the best interests of the child as to per se raise a strong probability that the offending parent is unfit to act as a custodial parent.