Modifying 5e automated rules (using long rest healing as an example)
I am very new to FantasyGrounds (joined with the kickstarter for Unity), and I'm trying to learn as much as I can about the program and how I can modify its automated processes for use with my homebrew rules for a 5e campaign. I figured a reasonably easy yet maybe complicated thing to start with would be to modify the long and short rest healing rules to match the way I've been running my game. The Basic Extension Coding Tutorial by Damned has been really helpful in getting me started, but I am stuck on trying to modify the healing options without copying the entire file. I know you can use merge with things like windowclass, but what would the proper method be for modifying a function, or something in a function?
For example, I want to use the slow natural healing variant as a base, since it's similar to the way my healing rule works. Instead of healing full HP, characters only heal 1/4 of their max HP with a long rest, but still recover half their HD. They can increase this to 50% HP and 75% HD by taking a full day of rest rather than 8 hours. On a short rest, the players are limited to spending up to 50% of their max HD (this doesn't really need to be included as a rule, since they can limit the number they spend very easily).
I identified the slow natural heal string, and made a strings xml file with a new string name for my option following the steps in the video, and found that the healing option names are called in the data options lua file. My thought was to create a file that would modify just that options line so that it includes my option (and then also the line that refers to which option is selected in the character manager lua file so that the rule would apply when the option is selected). However, I'm not sure how to do this.
What's the best way to go about changing the automated rules? Should I be creating a layered ruleset (in which case, I'll need some more help there too), or is there a more direct way to do this? Ideally I'd like to code it so that any updates to the 5e ruleset would automatically still be applied, regardless of if I am over-riding part of it with a custom rule.
Thanks in advance!