Assuming you use IS Boxer, you have two approaches to a Death Grip round-robin.

You could go with Send Keybind to Group: (all of) Death Knights.
And check the box, round-robin within target group.

That approach uses the order the toons appear within the Action Target Group.

I actually have a mapped key for Death & Decay set up this way.
It sends the Keybind for Death & Decay to the DK ATG, with the check to round-robin within target group.
It also Sends Next Click to the DK ATG, also with the check to round-robin within the target group.
Since it is the same ATG, the Death & Decay + Mouse Broadcast to only one toon at a time always syncs up.



The other approach, is the original round-robin method.

If you have four DK's on your team, and want something to be round-robin.
We used to go with four steps.
And each DK does something on each step.
-- Step 1 > Death Grip keybind to DK 1.
-- Step 2 > Death Grip keybind to DK 2.
-- Etc... naturally including FTL Assist Me, prior to the keybind.

Just extend that, so the modified Step 1 reads.
- FTL Assist Me, Target: Current Window
- Send Death Grip keybind to DK 1.
- Send Outbreak keybind to DK 2.

Then do the same with the other steps.



You can check the box, "Do Not Advance to Next Step" and check, "For At Least" and fill something in like 0.2 or 0.3 seconds.