I have a letter that directly concerns the history of your family. In the letter of 1911 it explains the Lafayette association. The Permars were living and farming on the Eastern Shore of Maryland during the Revolutionary War. The letter of 1911 goes on to say William enlisted and fought 'alongside Lafayette'. (There is a William Palmour in the muster roll for MD).According to troop movements at this time yes, it is completely possible William Permar joined in and fought with Lafayette. Washington , Gen Green and Lafayette camped so close to the British who had landed at Elk Head MD that they risked capture. From this point they proceeded through Tuckahoe Hundred in Queen's County Maryland (became Caroline County MD) where the Permars were farmers. Then Washington and Lafayette moved upwards into Pennsylvania to the Brandywine Creek Valley where they engaged in the Battle of Brandywine with the British. (and lost)
The fact that William Permar who died in 1779 is the grandfather of Henry Permar (PA farmer Delaware County) father of James Permar (father of Henry farmed in MD) and father of John Permar (who moved to Ohio when his mother remarried after William's death and founded the clan there) can be proved by the family letter of 1911 PLUS census documents in Maryland from 1776, 1778, 1790, 1800 and 1810.They are all online.
Contact me for more information concerning any of this.