My question involves name change laws in the State of: California

My ex-husband has agreed to hyphenate their step-father's name. He was hesitant at first but after talking to both kids and hearing their side of why they wanted to change their names, he has agreed to file the paperwork together. He's been very adamant about getting copies of the name change paperwork which makes me wonder what (if anything) he can do now that he has signed the papers and agreed to the name change.

I'd like to know if it is possible for him to try and stop paying child support as a result of agreeing to the name change.

Kelly