[Bug?] Possible error in costs of Merits

[Noctifer]

...this may not actually be a bug, depending on how you view the MET rules for WoD.

From the MET World of Darkness book, pp. 310-311:

"Note that some Merits can be purchased all at once, while others must be purchased one dot at a time. Merits that increase incrementally and/or bestow different benefits at each dot, such as Fighting Styles, must be purchased dot by dot. Merits such as Inspiring that confer only one benefit are purchased all at once. For example, Peter’s character has two dots in Fighting Style: Boxing and Peter wants to raise it to three dots. Later in the chronicle he wants his character to acquire the Inspiring Merit. Assuming he receives Storyteller permission and justifies the trait increases in-game, a third dot in the Fighting Style Merit costs six experience points (new dots x 2). By contrast, Inspiring’s four dots are acquired all at once and cost eight experience points. Peter can’t go from no dots in Fighting Style to three dots. He first needs to acquire one and then two dots on separate occasions."

I take this to be something of an errata to the tabletop rules, which is much more vague on how Merits are purchased.

Herolab's World of Darkness package doesn't currently include the differences in XP cost between incremental Merits and flat-rate Merits. While I understand this might not be viewed as a bug if you take the stance that its one of the differences between the tabletop rules and the LARP rules, I'm using HeroLab to design LARP characters, so I need to fix this.

I'm more than happy to do the edits to flat-rate Merits myself, but I'm uncertain of how to code the change in XP cost. I've a basic understanding of how to use the Editor (I've used it for both Pathfinder and WoD), creating new Merits, Bloodlines, etc. My problem is writing up the script to the XP cost.

Any hints/suggestions/help is appreciated.