Ingame you need a different macro for each DK.

For example:

DK1 /castsequence Chains of Ice, DG, Blood Strike
DK2 /castsequence DG, Blood Strike, Chains of Ice


I round robin Frost Nova on 7 mages.

I'll be round robin Chain Heal on Shaman.

I would round robin War Stomp if I had enough Taruns.