Hi,
You will need to point the Search Head to Master Node. Search Head will discover the Search Peer via Master Node. You do not need to add Search Peer in Search Head.
If you want to do it via Web Console, do this on the Search Head.
http://docs.splunk.com/Documentation/Splunk/7.0.2/Indexer/Enablethesearchhead#Enable_the_search_head_2
If you want to do it via CLI, follow these steps on Search Head.
"Integrate with a single-site indexer cluster"
http://docs.splunk.com/Documentation/Splunk/7.0.2/DistSearch/SHCandindexercluster
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