Shulchan Aruch (Yoreh Deah) 345:5 states: Those who deviate from the ways of the community, i.e. people who have thrown off the responsibility of mitzvoth from their shoulders, and are not included in the Jewish people concerning rituals.
As I understand this applies not to mourn the person for 11/12 months. But my question is the family who as well consented to the cremation are they allowed to have a memorial plaque in the Shul, Commemorating the anniversary of the death?