Ah, gotcha. See, part of me not wanting to share the game I'm making is that I don't want to deal with the pressures to try and monetize it or deal with trying to make it platform friendly in that way.
Plus, if I had to actually write out "step-twin" I think I'd go so insane if have to join the Looney Tunes
If you didn't already know this, you can make all the 'wrong' relationships and ages (and names) into variables within the descriptive text. Then simply allow the player to enter their preferred relationship and name. Ages available likely still need to be within 'allowed' ranges to be monetized via some sites. If you make it simple to see what the age variable is, and make it just as simple to see what the 'defense' against changing it to an 'unaccaptable' range is, the age modding will be done for you. What I mean is that the TWINE java (or w/e it is) can be leveraged to make the core game what it needs to be and as long as the default relationships and names
within the distributed game are 'clean' for the censors, the player can uncensor the game, and a modder can fix other stuff in seconds.
Example:
Mother character might need a few names and relationships:
Her given name [Default: Joanna, player can type in a preferred name, like Elizabeth, or whatever]
Her nickname/familiar name [Default: Jo, player can type in 'Liz', or...]
What the protagonist (and perhaps other 'housemates') calls her formally [Default: Landlady, player can type in 'Mother' (Aunt...)]
What the protagonist (or a particulat 'housemate') call her informally [Default: Lady/Ma'am, players can put in 'Mom' etc]
What the Mother refers to the Protagonist as when not calling him (or whatever) by his name [Default: my tenant, players can enter 'Son' etc]
What the Mother calls the other 'housemates' [Default: my tenant, players can put in daughter/niece/son etc]
While you write the game, you keep the correct names for your story within the variable defaults so that you see it as you intend it, save it, make a copy, then write a script
within the copy to change the defaults to the 'acceptable' defaults, and have an intro that allows the player to enter his chosen names and relationships. It can get complex, but it's common enough to various extents within the text games I've partaken of.