Brainwashing

My son has repeatedly told me that he is not supposed to use his birth last name, but to use his stepfather's last name. He is 10 yrs. old and I'm concerned that this will have a detrimental effect on him in years to come.
Does anybody know of any legal action I can take to stop this from continuing?
I live in NJ, and my son lives in NY. Also, I pay weekly support and have by-weekly visitation.

Providing they use his proper name on legal documents then your only real approach is to document it all and wait for something bigger. This on its own is not enough for anything. It is a form of PAS, but there would have to be so much more before action could be taken.