How does partnership in mitzvah performance relate to the reward allotment for that mitzvah?

Shiur #55 in Rav Aharon Kahn’s Hashkafah Series Based on Mishlei with Biur HaGra.

Content Description: Discussion of how reward gets apportioned among partners. Further sources regarding whether or not a person can make stipulations regarding the rewards he has earned.

Citations: Teshuvas Afraksa di-anya, 1st chelek, siman 58, found in the source packets on pages 1-3, and Teshuvas Tsits Eliezer, fifteenth chelek, siman 3, found in the source packets on pages 3-5.