Children's rights in visitation

I have sole physical and legal custody of my daughters (age 14 & 15) - always have. Their father has only had supervised visits and has utilized these visits only 5 times in the past 11 years.

I was served recently with custody and visitation modification papers in which he is now asking for custody - and if not granted, wants the supervision removed so they will spent summers with him. My daughters do not want to have any contact with him (I even have to force them to call him twice a week for his phone visitation).

My question is ... do my daughters have "rights" at their age in which to decide custody and visitation with their father? Are they of a legal age in which they are allowed to either call him - or not - see him - or not- ... at their choice? I have told them this is a decision that is up to them - to think about what they want. And they are very stern concerning wanting "no contact" with him.

Any suggestions? I have a court date set for January ... and (as of now) do not have an attorney and am on a "limited budget" (as most single mothers are I imagine). Thank you for any information you can provide ... P.S. The state we live in is California.