aenhancers

I'm working on a tracking project, and I'm getting quite frustrated with the inability to position your target layer anywhere in the comp. Attach points can't help me because I'm tracking a layer for Position and Scale, hence having two track points (and I positon these track points on the brightest, most contrasted dots of my image), and I need my targe layer to be somewhere between the two track points.

I figure it must be possible to have an expression that will offset the values given by the tracker by a certain amount of pixels so that I can position my target layer wherever I want in the comp?

Alex