How should a convert conduct himself when his biological parent dies a) in regard to attending the parent’s funeral (chillul hashem in the eyes of the non-Jewish family members if he does not attend; problem of location of funeral such a Christian graveyard) b) in regard to sitting shiva (the people in the convert’s community are not aware that the deceased parent was not Jewish; the convert himself needs a certain period to "digest" the fact of the parent’s death) c) yizkor (not saying something when everyone says yizkor feels being deprived of an expression of love and mourning)

ערב ראש חודש מנ"א אב תש"ע 1. One may participate in the funeral of gentiles, on the condition that there are no Christian symbols as part of the funeral. (Yoreh De'ah 369:a and Da'at Tora (ibid) of the Maharsham.) 2. Rav Mordechai Eliyahu zt"l in his book Tzror Hachaim says he sits Shivah. 3. Although a convert is considered reborn and not related to his biological parents, a memorial prayer may be said by somewhat concealing the name of the deceased.(B'mareh Habazak part I, 70) Besorot Tovot