Lovin' And Leavin'

Denise and Mark discuss situations where parents are using their children as weapons against each other. How does one do that? Some parents control access to the children by being inflexible with parenting time; others will make things purposefully inconvenient, like extracurricular activities or doctor appointments, in order to affect or exclude the other spouse. Some parents go so far as to alienate or poison the relationship of the children with their spouse. How is this accomplished? Does it fly in court? Is there any way to fix it?