Copy glyphs into all Instance while exporting

I’m working on a font family with 3 different weights. Along with the normal glyphs-set comes a stylistic set of hairline-weight punctuation and symbols that remain the same weight in all masters.
So far I have the stylistic set drawn in the Regular master while it remains empty in the other masters. Obviously I could copy them, but that’s not really a smart workflow. Is there a way to batch copy selected glyphs from one master into the other masters.
Or even more useful: Is there a way to include glyphs from one instance in another instance directly while exporting the font files? That would mean I wouldn’t have to update the drawing in all masters all the time.
Short: Can I draw glyphs in one master and have them unchanged included in all instances when exporting?

Thank you