Troy,
Although I'm not quite sure I understand exactly what the fixture(s) look(s) like, it sounds to me like you need to generate a primary alignment plane that is based on the offsets from points that are located a specified distance from the primary plane. If this is the case, then the easiest method would be to use a function that may be built into your CMM software. I use DEA's Tutor v7.1 for DOS and it has such a function. It's called "3-level plane" and it works perfectly for what you're describing. The only caveat is that the 3 probed points are "supposed" to be on 3 parallel planes (although I've developed a workaround for this). The user of this function need only enter the 3 offset values and the software automatically generates the plane. If I'm not understanding what you're trying to convey, please try to provide more of a description and if at all possible, attach either a bitmapped (.gif, .jpg, .bmp, etc.) file or CAD-generated file of the fixture(s) in your reply. Alternatively, you can send me email. I'd be more than happy to help you resolve your problem; I know what it's like trying to get procedure-specific info on a problem. Good luck if I don't hear from you.

Shane