Copying specific kerning pairs between masters

I’m trying to copying specific kern classes from a bold master to a light, just the @period and @hyphen. When I select those only and paste into the light master kerning window it says “there is already kerning” with overwrite and keep options. There is kerning but not these classes. It seems to wanting to copy the entire kerning data — which has caused quite a kerfuffle in locating the last safe file :expressionless:

Version 2.4.1 (976)