No understanding of creating group kerning

I do understand the neg. and pos. space concept of kerning (doing it for years)
I do not understand how I can cet my french accent a- -i etc. to behave and sit with the same side bearings and kerning as my English a. ( read the manual countless time).
Is there a simple explanation some one can share. Screen Shot 2021-04-23 at 3.49.28 PM

Have you read this: Kerning | Glyphs