I realize that this is probably a long shot...but is there any information on a David Barr?
What I know of David is that he was born about 1794. He emmigrated to New Brunswick, Canada in leaving Port Glasgow on the 22nd of October 1815 and arrived in St. John, New Brunswick in March of 1816.
According to other papers when he petitioned for land in N.B., the paperwork stated that for the last five years, 4 were in N.B. and the year before was in Port Glasgow.
I have no knowledge of family that he left behind or their names. That is all I know of his time in Scotland.