How to add sizing of ancillary support on pipe support detail?

You could probably copy RTEX syntax into STEX and add an expression to grab the PIPE Size.

Then you could customize support drawing creation so that it takes STEX instead of RTEX in the MTO

Thank you for your answer. I found the better solution, I just modified some syntax on MdsAbaMtoComp.pmlobj
ex :

!size = !tempelements[$!subs].dbref().ppbore[1].string(!boreFormat)
!this.elements[2].append(!tempString + ' ' + !description + ' PIPING SIZE:' + !size)