A followup to this, for those interested.
NozzlePro cannot handle this natively, but you can pass ownership of the NozzlePro file to FE/Pipe in the options dialogue to do this.
• Once you have your Nozzlepro file set up, make a backup.
• Plot your file. Click View>Stamps>Plate points. Note the points on your plates that are in the wrong location.
• Hit the Options button.
• Activate all the FE/Pipe options in the lower left corner. Once you do this, you cannot undo this, and you are forever tethered to FE/Pipe input for this NozzlePro file.
• Click Plot, and instead of plotting, it'll open FE/Pipe.
• Click 7-Plate Geometry
• Click Plate Points [F7]
• Note several tabs with Point IDs. Note that tab number is not the same as point ID number.
• Adjust the values here to reflect reality. S=Surface, C=Centerline, D=Delta, and A=Absolute
It seems like one might be able to make some interesting geometry that's not really covered by NozzlePro default. For example, if you welded a brace to a mainline and a pipe.