It is stated in the sutras that every participant in the liberation of living beings will gather the full amount of merit thereof. For example, if one hundred people were to kill one person, this bad karma would not be divided among the hundred but borne completely by each one. The same goes for virtuous deeds. If one hundred people were to set one life free, everyone would collect the whole merit of freeing one life, not just one percent of it. Over the years, we have freed billions of lives in this part of China and all the merit accumulated thus far belongs to every participant. Just liberating living beings is already an incredibly virtuous practice. When it is conducted together with unselfish motivation and proper dedication, it will garner even more inconceivable merit which undoubtedly can purify all our negative karma.

- Quote from The Right View, "Liberating Living Beings"