I have two stand alone indexers that are also search heads, I would like to cluster these indexers, can this be done with the search head functionality enabled or do I need to separate search heads?
When you identify a Splunk instance as a component of a cluster, you either need to identify it as 1) cluster master process 2) indexing peer 3) search head.
At least through the GUI, there is no way I know of to make an indexer also a search head.