Would you be naming it Mac Falconer in order to distinguish it from the tartan previously known as Prince, errr ... Falconer?
If so why not name it Falconer of Motherwell, since you took the trouble of desiging it. Or is there a location that the Falconers are associated with that you could use.
I'm sure there's no rule against using Mac Falconer, I was just tossing out other possibilities.