Don't mean to be negative and I will get some serious wrath here. This forum cannot teach GD&T or teach you to program from scratch. We can assist for sure. How long have you been an inspector and working with CMM ?
Apologies can't visualize how tooling balls all on same plane can constrain in 6dof of a part?
Imagine one tooling ball fixed in space. That point is locked in X, Y, Z or 3 DOF. However it can rotate all over in the other 3 DOF. Now imagine locking down the location of the 2nd tooling ball. Now not only can't it move in X, Y, Z, it also can only rotate around the axis created by the 2 tooling balls. Imagine a line between them and the part can only rotate around that line, or there is just 1 DOF left to constrain. Now when you lock down the 3rd tooling ball the part is solidly fixed in space, all 6 DOF are constrained.
If you prefer standard geometry, you can create a plane from the 3 tooling balls and then create a circle from the 3 tooling balls and a line between 2 tooling balls. Level to the plane, rotate to the line, and set X Y origin on circle and Z origin on plane.