Change of visiting arrangements: Legal Advice

Questioner

My sister and her ex-husband have a 12-year-old son. They separated 10 years ago. Sister has (I think) parental authority. A contact arrangement was established during the divorce, whereby the son goes to his father once every two weeks for a weekend (Friday evening to Sunday evening). In recent years, the arrangement was first extended to Monday morning at my sister's request (mid-2007). Later, at his request, the arrangement was extended to Thursday evening to Tuesday morning (August 2014). Because it became complicated with who was responsible for which care tasks, it was agreed (June 2015) that all care (dentist, doctor, optician, etc.) would be provided by my sister. In order to be able to organize this practically, the son is with his father once every two weeks from Thursday evening to Monday morning. My sister suspects her ex is an alcoholic. She has no hard arguments (for example, son is not abused or anything) but sees that her son is not happy with his father. Father is satisfied with the current situation. Are there legal possibilities to re-establish the contact arrangements as they were determined by the judge during the divorce? Or has a kind of customary law emerged due to the course of events in recent years?

Lawyer

A petition can be filed to change the contact arrangement as it is now. Given the fact that the son is now 12 years old, he will also be heard by the juvenile court judge about this. If he indicates that he wants to see his father less, such a request certainly has a chance of success. If you wish, you can contact me.