Can you help me: Searching for McAllister History

[jasonm_mcallister]

I have been trying to trace back my family history. There are so many variations with the McAllister name that it is so hard to find where my family came from.
If someone could help me I would appreciate it so much.
This is what I have:
My grandfather James McAllister (I know he was at least James II or he could be the 3rd or 4th or so on) He came to America from scotland when he was 13 which would be around 1926. The last I heard, he was a tugboat operator in Philidelphia. He had a sister named either Margret or Peggy McAllister. MY grandmother Ruth Mclaughlin says she remembers calling her Peggy. James had my father Raymond James McAllister.
This is all i have so far.

My family has been torn apart by divorces so it is very difficult to trace back any futher than this.

I would love to know where the name McAllister came from and if this was part of the McAllister clan that I have heard so much about.

Any help would be greatly appreciated

Thank you
Jason McAllister