This is a reverse engineering type problem. I have these two parts and I need to mate then in relation to each other. On the part called "Circle" there are three protrusions that are circular. I can measure the distance from the edges of the block to the circle and then reproduce that with a mate. The issue is that the mate I really need would be a distance between the edge of the circle to the edge of the block. If I could do three mates like that then I could accurately place the part on the block.

This is an idealized case as I cannot post the real problem. On the real problem I cannot identify the points where the circles intersect with the spline, they are tangent and very hard to see so the mate needs to be a tangent or distance to the edge which SolidWorks seems to not want to allow.

Any ideas on how to mate/place the "circle" on the block with some accuracy using measurements from the actual part?