Hmmm ... 2 separate battles is a different beast - there can only be one battle at a time.
However, you could just have it be one battle, though make sure to either disable the different battle ranges (and AI ranges) in Battles > Battle System > General Settings or make them large enough to cover both battles.
Once the other combatants join in, they'll also be part of the battle, with use ranges for your actions you can limit them to only attack the targets in their area.
Click movement for your units could be handled by an ability. Using None target range (i.e. not targeting a single combatant or group) allows having raycast targeting to click a position - the position is available in the schematics animating your actions (as Starting Object), i.e. you can just move there via movement nodes (or setting a NavMesh agent's destination, etc.).