Make up hydrogen gas compressor pressure control

We are having a reciprocating compressor three stages and three train that is utilised for supplying hydrogen to the Hydrocracker and hydrotreater from second stage discharge (80bar)
Suction pressure:22 bar
Third discharge pressure =178bar
Each train has individual spill back and there is common spillback.How we can control reciprocating compressor first,second ,third stages and Hydrogen to Hydrotreater unit?