Gap for buttweld

Our shop would like the gap required for a full penetrationweld to be included in our routes. We have moved the c-point on ourflanges to accomplish this but that approach does not work verywell with other fittings. When we put fitting to fitting runstogether the gap doubles because you have two offsets.
I have found mention of adding a custom specified parameter. Can Iuse this option to create a gap that can then be controlled throughthe design table?
If so how?SolidworksRouting