Rockland County pre-Revolutionary sources

I have an ancestor, Samuel Garrison, born about 1740 I'd guess. He was captured at the Battle of Ft. Montgomery on October 6 1777 and died in a NYC prison. I'm trying my darndest to honor his life by submitting an app to DAR but I have been unable to definitively link his son, Samuel, to him.

I do not know the wife of Samuel< Sr. (who would also be the mother of Samuel, Jr.) I am certain of Samuel, Jrs. existence as he and his brother, John, petitioned for and were granted bounty land in upstate Sterling Township. Neither Samuel nor John moved to Sterling Township, the land was delivered to a William Willets as agent for John Allison. I've been trying to connect the Allison surname as Samuel enlisted and served with Allisons but so far to no avail.

There are a few Samuel Garrisons in the area at that time and I have been unable to rule out any.

I SUSPECT that john and Samuel have different mothers, but I have been unable to prove this.

I'd appreciate any hints as to where else to look.