link characters from custom properties in drawing

Hello,

Is it possible to link only a few characters of a custom property in a drawing?

exemple:

We save each part file as a number . for example 333555,

in the drawing we link the file name of the part to a drawing number.

If the part has a revision, we save it with a different filenumber. 333555A (to keep also the old revisions, and no we don't have pdm)

I still want in the drawing as drawing number 333555, and not 333555A, and i would like to be the A displayed in the revisionbox..

I don't think this is possible, but i'll ask anyway :-)

SolidworksDrawings And Detailing