1. Question: How is it possible to fulfill the mitzvah of matanos li’evyonim when giving it to a father and son where the son is still dependent on the father?
A. The mitzvah of matanos li’evyonim is two give money enough for a meal to two people.
B. The Aruch HaShulchan (693:2) says that if you give to a husband and wife or a father and son or daughter who relies on their parents for food it is not considered giving to two poor people, rather to only one poor person.
Answer: The Responsa Hisorirus Teshuva (3:489) says that if you give the father and son on condition that the father has no permission to touch the son’s portion then you fulfill the mitzvah. (Dirshu Mishna Berura back page 134 footnote 13)