I've recently created a new multisite indexer and search head cluster topology, using separate VM''s for my license server and cluster master. I have an additional VM which I am going to use for one, or all of the following roles:
I am considering one of two options:
Place all three (Deployer, Deployment Server & DMC) onto my remaining VM.
Place my Deployment Server on my Cluster Master
Place my Deployer on my License Master
Place my DMC by itself on the new VM
I should point out that my Cluster Master serves as Indexer Cluster Master, as well as Search Head Cluster Master (not even sure if these can be separate)
DMC instance is required to be a search head of the indexer cluster, which means in either Option A or Option B, you need to convert DMC instance to a search head by clicking "Settings -> indexer cluster", then enable indexer cluster and choose role as search head node, point this instance to the indexer cluster master.
DMC instance is required to NOT be a search head cluster member. Actually DMC will be disabled on search head cluster members. So in your case, the DMC instance will be part of the indexer cluster but cannot be part of the search head cluster.