Feature request: the ability to share components across masters

Glyphs
10

Using a component of a glyph in the same glyph is not possible. What you can do instead is use a script to copy the paths from one master to the other, which you can run whenever you want to ensure consistency.

For your setup, if I understand correctly, the following would work:

for layer in Font.selectedLayers:
	source = layer.parent.layers[1]
	layer.shapes = source.shapes.copy()
	layer.anchors = source.anchors.copy()
	layer.width = source.width
	layer.hints = source.hints.copy()

This copies everything from your second master to the layers you currently have selected. So make sure you are in your first master when selecting the respective glyphs.

Components between masters