On Cmd+Opt+Shift+C a pop-up could appear which asks to use the base glyph as new kerning group value (if empty).
The same while adding known glyphs through a list filter or through Cmd+Shift+G.
For multiple glyphs this pop-up needs a list of check boxes …
You mean, copy the kerning groups of the component (e.g., a) to the compound glyph (e.g., adieresis)?
Actually, Georg’s Set Kerning Groups script does exactly that already.
This would slow down component handling significantly. A better place for this function would be the context menu of the component.
OK, that’s right.
What could be a better way to (semi-)automate it?
For most Latin and Cyrillic glyphs a fully automated kerning group would be OK!. Comparable to auto-metrics.
From the top of my head, I can think at least of Ldot, dcaron, and lcaron, where the right kerning groups should not be inherited. But the idea is interesting, we’ll think about it.