Group Initiative API change to d20?

Is there a way to alter Group Initiative API to roll just 1d20 + the players dex mod? The API seems a bit unbalanced rolling a bunch of values that I don't even know where they are coming from. My players are rolling actual dice for their own initiatives and I wish to use the Group Initiative API just to add them to the Turn Order and simultaneously roll for the monsters but only using the d20 + the enemies dex mod.  I can't figure out how to edit the script in any way.  Help appreciated!

That API currently has the default bonus added to rolls to be set to the dexterity score, instead of the dexterity modifier. The documentation specifies how to change this. First, you need to remove that bonus, using this command "!group-init --del-group 1". This will remove that modifier. Then you can add a new modifier which if your using 5E rules is the dexterity modifier. You do this using the add group command referencing the dexterity modifier which could be different depending on what sheet your using. If your using the shaped sheet then, "!group-init --addgroup --bare dexterity_mod" should work. When finished, using the standard command with tokens selected should roll 1d20 + the dex mod for each token.

David has the right of it. Let me know if you have any other issues. 

I have done this but the macro still adds things that do not make any sense. There is only 1 group listed: dex_mod. But I am getting roll results that are impossible for the character.  It is adding like 3 values.