Fixturing question

I know this isn't a Tormach-specific question, but you all are so helpful, that I figured this was as good a place as any!

The situation: I machine several parts for one of my products, that require many different fixture positions. So I have g59p8 through g59p12 set up for these different operations. I am using a vise, and I have a jig made to set each new piece exactly in the vise. So even though I'm using different size stock material for different parts, they are all referenced to the non-movable vise jaw.

Fairly regularly I need to remove the vise to do larger machining on the bed. When I put the vise back on, I straighten it and reset G54 (What I use for my vise home) to the new location.
Right now, I do the math for my 5 fixture locations g59p8-12 and enter them into the fixture table, since they are all derivative of the vise location. (E.g., -3.25" of g54 in X, +.788" in Z)

It seems to me that there must be either a better way of doing this in G-code, or a maybe a way to write a macro in Mach3 to automate the repopulation of the fixture table.
Any suggestions? Thanks.