AskGlyphs: Can I auto-generate a master from 2 existing Masters?

I already have two masters (weights: 100 and 900), can I auto-generate a master between these weights (say 400)?

Set up an instance at 400 in font info>instances, select it, push the + button and select »instance as master«.

If you need a master in the middle only for a few glyphs, you might be better of with brace layers:

@birdland Thanks. That works.

@GeorgSeifert Thanks. I am using the Bracket Trick. But I will try using the Brace layer trick as well.
Btw, there’s some issue with the markdown on this page: