It's in sync with the new in-game panel (see viewtopic.php?f=50&t=6106)
When you buy/offer units, they will go in a pool of "owned units", on the bottom-right on the interface.
You can drag&drop units into 5 groups. These 5 groups will appears in the same order in FA.
You can move units from a group to another group, or back to the pool of owned units.
It's up to you to manage your groups as you wish.
As long as you don't call the reinforcement in game, they are not consumed.
Also, you really don't need to build the beacon first anymore.