Thanks for being so responsive. As to mod friendliness, I think you did indeed intend that, but as far as modding it back to the
original relationships, the dialog and sentence structure contain hard-coded words that do not lend themselves to simple variable substitution.
You may wish to consider the sentence structure of the dialogs OR make notes where you hard-coded the foreign-exchange student idea into the sentence. As it stands now, a 'translation' patch would be required to fully revert to the daughter idea. It's doable, but the problem is that RenPy translation files do exact text matching, so every time you modified a dialog line, the translation would break. Only someone with an extreme dedication and copious free time could consider taking on such a project long term.
In closing, it's your work, and you take it the way you need or want it to go - no apologies needed. I am just mentioning this in case your
intent was to let modders change the relationships back. It's meant as constructive feedback to make sure your intents and efforts are in alignment. You don't owe us anything.