That's a hard topic. If you're using the shaped sheet, it's actually quite easy: !group-init ---del-group 1
!group-init-config --set-dice-count|0
!group-init --add-group --bare initiative_formula
This is because the shaped sheet handles the mechanics of advantage (and halfling luck and other 5e rules) in it's formula, so removing the die and handling it that way works. YMMV though, based on what sheet you're using. I've got some ideas about how to handle it, but it's a complicated change and I'd like to roll it into some other changes...