What are the limits of a permissible relationship, Islamically, with a Baha'i maternal uncle, for the sake of maintaining kinship ties?

Baha'ism is based on corrupt, infidel doctrines, and its adherent is an infidel, outside the pale of Islam. Maintaining ties of kinship with an infidel is not obligatory, but it is recommended if there is hope of their entering Islam, or of a Muslim descending from their loins. The truth must be made clear to him, and the errors of this sect must be exposed to him, for guiding a person is better than red camels.