How can a search head and an indexer cluster be merged after the cluster has been run intentionally in a split brain setup for some time.
e.g. the connections between two locations of a multi site cluster is broken and a captain has been assigned manualy to the second site.
The scenario is well documented on the following Splunk docs:
Handle master site failure:
Restart indexing in multisite cluster after master restart or site failure
Ensure that the peer and search head nodes can find the new master