RPGM Question: Adding more than 4 characters who can fight?

[Sothyr]

I saw the first time in Harem from Ker that it is possible to change the number of characters who can fight in a game. I wonder if it is hard in other games or also in Harem to make it standard 5 or 6 characters in a fight instead of 4.

Is there something I can search in the code and change?