There are two meanings of pad, which are pcbnew and the footprint editor. So what do you mean pad here? And can you tell us the purpose of centering the grid to a pad?

Is it that the different footprints don't have the same pads? Footprints snap with their center to the grid, which is defined by the origin in the footprint editor.

I think it is possible do as you want, but not for single pads, unless you kept the spacing of the pads within the footprint on a similar spacing.