Adding a penalty to hiring mercenaries

[Xietor]

Anyone know how to add a 25 percent cost to a nation when it hires mercenaries? I am thinking that since a starting hero in my Beowulf mod allows for early expansion, a penalty should be imposed on hiring mercenaries.

That would prevent too rapid early expansion. I looked at nation modding, but see no way to add the Pangaea penalty to Man when they stat with Beowulf.