Manual centerlines. This may be old news.

I have a line of holes on an angle requiring a centerline. I can't just click two parallel edges of my part to place a centerline.

I just realized that you can draw a standard sketch line between the hole centers while in a drawing, and if you check the "construction line" box, the line becomes a center line.

Hopefully, this can benefit someone else.

SolidworksDrawings And Detailing