MY SISTER CONVERTED.SHE PASSED AWAY.SHE WAS CREMATED.AM I ALLOWED TO ADD A MEMORIAL LAMP TO THE YAHRZEIT BOARD IN HER MEMORY
It is permitted to add a memorial lamp.
Sources: Although there is no obligation to recite kaddish for one who coverted out of Judaism, many write that it is permitted to do so. The same principle would apply to lighting the memorial lamp. See Rema (Yoreh De’ah 376 (no obligation of kaddish); for those who nonetheless permit saying kaddish, see Shut Radach (Beis 30); Kesav Sofer (Yoreh De’ah 171); Chesed Le-Avraham (Tinyanah 81); and see Iggros Moshe Yoreh De’ah 4:61).