DAN_M Are you using PC-DMIS 2020 R2? If so, the new Geometric Tolerance command allows you to choose the math type used to evaluate your datum features, namely Least Squares or Default (Constrained L2 if ASME).
If you are not using 2020 R2, I believe PC-DMIS will evaluate datum feature B using whichever fitting algorithm you used when probing the feature.
Changing between "Datum Reference Frame" and "Current Alignment" should not change the way that PC-DMIS evaluates anything, it should simply change the reporting coordinate system. If you set your (current) alignment per the datum reference frame [A|B|C], there should be no difference in the report by changing between the two options.
