Adding a glyph into a kerning group

Hi! Is there a way to add glyphs into a kerning group through features/classes, instead of individual Glyph.leftKerningKey? I tried creating a class @MMK_R_… and adding some kerning for that group, but it’s ignored on export. However, if I assign that group name to a glyph, compiler complains that Duplicate definition of glyph class “@MMK_R_…” , which probably means Glyphs creates that class somewhere else, right? Any hints please?

Why do you try to do that?

To put a glyph into multiple groups and use different ones depending on the pair. Seems useful in theory, but who knows