Dowel pins are used to align two holes, and the parts they are in of course. Sometimes you want the dowel pins to stay with one part but be a sliding fit in the other. On a subplate probably the best idea is to have the sliding fit holes (i.e. 0.0005 oversize) so the pins release from this plate. On the fixtures that attach to the plate you have the interference fit (0.0005 undersize) so the dowel pins stay with this part.
An open mind is a virtue...so long as all the common sense has not leaked out.