At the risk of seeming self-centered, I offer Jace's Scots relatives: Clan Montgomery.
http://en.wikipedia.org/wiki/Clan_MontgomeryThe Montgomery clan has a long history of gaining (and occassionally losing) wealth and status. Legends surrounding the family hint at fae connections and blood ties (which may provide a pseudo explanation for the American branch of Montgomerys that Jace is part of). The fae connection in particular might provide some ideas: In the world of the X-Men, surely some variety of them might even still exist. (Perhaps a Sidhe takes an interest in one of the students or teachers, or just about anything else.)
And yes, Field Marshal, Bernard Montgomery, 1st Viscount Montgomery of Alamein, is part of the family. (Whose troops were largely responsable for expelling the Nazis from Africa, and then a prominent commander in Italy and North-West Europe, where he was in command of all Allied ground forces during Operation Overlord and then until after the Battle of Normandy.)
So if there is a need for a cast of Scotish eccentrics (Muir island personel, inhabitants of Stornoway or Ullapool), the Montgomery Clan is ripe for the taking. As I imagine them, they regard Jace's family as sort of "cousins made good" and still consider them part of the clan despite almost one hundred and fifty years of direct seperation. The clan bond remainds tight and the two branches remain in touch in family and business matters.