Make an Enemy have a never-ending army.

Let's say a boss can summon a couple of his guards. The problem is once you kill them, they can never come back. These guards are summoned with the "appear halfway" option. Can you make it so that as long as those guards are dead or not yet appeared, the boss can summon more guards. In this example, the boss can have up to 2 guards. He can only bring in more if he has less than 2. The new guards are still the old ones but revived. How can this be done?

You could always have the master use a Revival spell.

You can do this by giving the boss a revive skill which revives all KO'd enemies. Then those guards will revive and continue the battle. That's honestly the only easy way to do it too as there is no good way in the default engine to just add a new enemy short of the appear halfway option.

The way I've done this in my game is given the boss a skill which revives all allies, no MP cost. Then I have it invoke it at the end of the turn when I want them to use it. So if you want them to always have 2 guards, just invoke it at the end of every turn via troop events.