My son and his wife are divorced now, they have joint legal custody mother has primary physical custody because my son is in the military and he was told that she had to have primary physical custody in order to enroll the child in school. However she doesn't have my son listed as a contact person or a person that can pick his son up from school whenever he is home on leave. The mother says she has primary physical custody therefore she has more rights than my son. Is this correct?

To mother414. No the mother of your grandchild does not have more legal rights to their child then your son does. He should be listed on the school records and also be on there so he can get reports and report cards from the school. Also should something happen to the mother his name will be there as a contact in case critical decisions need to be made.
He can call the schools and have himself added and if they as or require a birth certificate he may need it or a copy of the court papers.
Also no the mother didn't need primary custody to enroll the child in school. Someone told a lie on that one.

No, first the mother did not have to have physcial custody issued, to enroll the child in school, joint legal custody was all that was needed, sounds like a good lie to give her more authority over the child, since now the child's father is limited to visitatin rights nor joint custody.
But in reality joint custody does not really work, when the child is with the mother, she will or can do what she wants, if the father objects, he has to drag mother back to court. Since they do not have equal custody the mother can do this since at this time, he now merely has visitation rights