Aliya: Being Called to the Torah
Question
Can a person getting an Aliyah to the Torah be called using the maternal’s grandfather’s name? If the father tries to take him away from Jewish tradition?
Answer
Shalom!
Thank you for your question.
Using a person’s Hebrew name to call him to the Torah is an ancient custom. The source for this practice is the Tosefta which teaches that one should read from the Torah unless one is specifically called to do so by the congregation. This applies even nowadays when the one called to the Torah only recites the blessings on the reading.
In the words of the Avnei Nezer: "You must know that this custom, along with many other customs, originates from the holiest of sources and contains deep secrets…God forbid to change the custom!”
As you correctly note, that custom is generally to use the father's name of the one being called to the Torah. This is true even if one is estranged from one’s father. The name of the biological father should be used regardless of the circumstances.
In very extenuating circumstances one who was adopted may be called to the Torah along with the name of his adoptive father, for example, if it is not public knowledge that he was adopted(each case would need to be asked by a rav). One whose father is not Jewish is called to the Torah using a grandfather's name (on his mother's side, of course) or as the son of "Avraham Avinu".
Source
Machzor Vitri p.72; OC 139:9, Avnei Nezer, CM 103; Lev Aryeh 1:55.