SKILL QUEUE SYSTEM FOR RM2K3

Hello community. I'm using RPG Maker 2003. I'm trying to make a battle system that each character has skills / spells that can be used, requiring another technique that has been previously used by the character. Like a skill queue system. My original idea is to make a series of techniques, including branching, to give a certain range in the manner of each fight.

For clarity, what I'm trying to say:
First round the character can use for example only the magic "Concentrate." If the character using this spell in the next turn he will release the use of "Fire," "Ice" and "Bolt". If he chooses the second round to use the spell "Fire" in the third round he can use the spell "Fire 2".
Please do not judge the example is somewhat simplistic only to better understanding of what I intend to do.

Meanwhile I'm thinking in something like this: character uses a skill which is part of a certain "combo", then his battle command changes by main event that is called by a fork in each Monster Groups. The next Skill subset will have the next spells of the "combo" and so on. But that my thinking has complications and is also very limited. I dont know if anyone has done anything like what I'm trying to do, I tried the search function of the forum and i didn't found any, if anyone has any idea of ​​an algorithm that I can do to reach my goal please help me
Thank you for your attention. Sorry for the bad english.

Thanks for the reply Craze. Your way seems much simpler than what I was thinking and it should work. I will try to apply it and return if something goes wrong.

That's exactly what I'm doing now, Large. The first step, which in our example is to use Concentrate to enable Fire works perfectly because the type of the first one skill is "switch".

The problem happens with skills that aren't of this "switch" type because then in the original system RM2k3 there isn't a possibility of doing a skill that gives damage or heal to activate a switch to be used since only switch type skills can do it.
The conditional branch inside battle events doesn't allow you to use the skill used by a particular hero as a condition, only the battle command used by this hero.

For now I thought of two ways to escape this problem. The first would be to make an exchange of battle command used every skill so that I could use the existing conditional branch in the Monster Group events. The other way would be to make all the skills of the game to switch the type, as well as Concentrate, and arrange their effects entirely by events (which would give a lot of work and also would limit the skills).