How to expand my combine?:SI
Only the CEO is able to increase/"expand" a Combine. The CEO must use resources to expand the size of the Combine in increments of 10 members per expansion. The cost goes up each for each expansion.
Go to your Joint Ops Center building and then click my combine (for CEO only) then right under Territory is a small button labeled expand, if you click it will ask for the amount of resources to expand your combine by 10 members.