What resources did you use to make your connection to PEI Loyalists? I have checked every muster roll and regiment on the Loyalist web site and came up empty for the name William McGlasher. I even hired a Loyalist genealogist to find him and he came up empty as well. Seems William is as much of a mystery as John C is.
I also have gone over the PEI map that lists the names of the land owners without success.