Aligning to a pattern

Aligning to a pattern

What is the ideal way to align to a pattern of holes? What I had been doing for the attached part, was setting my origin to Datum A, then aligning to one the holes for Datum B. After some discussion with Engineering, they said the pattern itself was the Datum B, not a specific hole. I can create a line between two of the holes, and align to that, but I figured there's probably a better way to align to the entire pattern.