5E Exploding Damage Dice and Global Damage Mods

So i'm running a game with friends and we love using exploding dice for crits (Because it actually feels like a reward), however I am having an issue figuring out how to make a Global Damage Mod which when checked off will re-roll max damage dice when you crit, but just roll normal damage otherwise.  I currently have this as the Macro; Searing Smite:  [[ ?{Level?|1, 2d8|1 (Crit), 4d8!|2, 3d8|2 (Crit), 6d8!|3, 4d8|3 (Crit), 8d8!} ]]  It allows the player to choose what level they are casting the ability at, and whether the attack roll was a crit, however the issue is Roll20 automatically doubles dice on its own when you roll a critical which adds double dice already. Ive also tried doing it this way; [[ ?{Level?|1, 2d8|1 (Crit), 2d8!|2, 3d8|2 (Crit), 3d8!|3, 4d8|3 (Crit), 4d8!} ]] however there is no section for Crit Damage on the Global Damage Modifier field and that results in only half the dice being rolled as exploding dice. Does anyone know a work-around or a possible API i can install which would automatically do this, or an option to turn off Roll20's dice doubling? Thanks in advance guys.

If you're talking about an attack listed in the Attacks & Spellcasting section, you should be able to remove the crit damage. If you click the cog to edit the attack's settings, under damage it should have a crit field. By default it should have grey text saying 1d6: this means it will use the default value which is to reroll the dice specified in the Damage field a second time. If you set the crit field to "0" instead of the default, it will roll a 0 for crit damage. I'm not sure this is the ideal way to achieve what you want, but it's an easy way to disable crit dice on a per-Attack/Spell basis.