My wife`s parents are non-muslims burried in a cemetery in a non-muslim section. There is a muslim section that is full and not available anymore. My wife desires for both of us to be burried in the same cemetery as her parents. Is it permissable for us to be burried there?

All praise be to Allah, and may his peace and blessings be on the last and best prophet and messenger, Muhammad.

A Muslim may not be buried with non-Muslims, nor should non-Muslims be buried in Muslim graveyards.
In case of necessity, such as the complete lack of Muslim graveyards in a certain town and the close by towns, it would be allowable for a Muslim to get buried in a non-Muslim graveyard.

Allah knows best.