just created an extenstion and put it up on FG Forge.
This extension will put 2 icons at the bottom of the GMs combat tracker. After rolling the initiative for everybody, the Alternating Initiative button can be pressed to change the order of the combatants to follow The Simple Initiative System described here:
https://youtu.be/SXleyDvtqls - Taking20 Youtube video describing the Alternating Initiative idea
The combatant with the highest initiative will go first, then the combatant with the highest initiative of the opposite faction will go, then the next highest of the first faction, etc. alternating between factions.
Combatants of the same faction that roll the same initiative will be lumped together.
Also, if needed (say if a new combatant will be entering the mix), the GM can hit the other button and the initiatives will be reset to the original rolls.
Attachment 56588
Attachment 56589
you can grab it at https://forge.fantasygrounds.com/shop/items/1088/view