See screencap for reference... this model is to be comprised primarily of two pieces of sheet metal -- the yellow face we see along with the four sides, and the back face we can't see (We won't get in to that inner "frame").  The face we see has a split line rectangle, denoting a line to be etched on the laser.  This is something we do all the time -- what's different and new to me is the modeling method.  We began modeling things as multibody parts, then splitting them out into unique parts.  Unfortunately it seems that to access a flat pattern, once I've saved the individual bodies out, I have to delete the sheet metal feature from the tree and then convert the part to sheet metal.  When doing this, I don't see a way to select the face on the 'inside' of the split line.  Executing the feature then eliminates that entire interior zone.  How do I go about achieving the result I want?

Thanks all!