Children are entitled by law to have a voice in issues that affect them. If your children are to be given a voice (not a choice) the usual way is by having them meet with a skilled professional who will listen to them and report back to you on what they said assuming the children provide their permission for that to happen. Preparing a Voice of the Child Report means that both parents have a neutral party helping them to hear their children’s voices.
Link to Hear the Child Society
Link to my VOC introductory materials