Literally all he has to do is make the two girls he lives with his half siblings and the landlady just a step mom type figure. Dad could have easily banged MC's mom and their mom too. EZ
Still, if he just arbitrarily makes them related, it feels forced instead of natural. With the two sisters in the previous game, it was natural because it was that way from the start. Again, I haven't played Eternum yet, so this is assuming they are unrelated as of now with no plan for them to be related. If he were to just arbitrarily change their relationship, sure, it adds incest, but not only does that risk the anger of Patreon, it also feels entirely forced at this point as if he just added it to appeal to the incest crowd. Even as an incest lover myself, I would rather the relation be natural, not forced.
What may seem easy isn't necessarily and, even if it actually is easy, it isn't always the right way to do things.
And then spend a lot of time each update to change the actual dialogue to have it make sense changing the characters background etc.
Anyone who wants to spend that time good for them. I won't be using it even though I enjoy incest this vn wasn't written with it in mind so to me not worth it...
But eh that's just me...
SerHawkes stated he might create one after its finished so there is hope for those that are craving it I guess...
Yep, unless a VN has incest taken into account in its story, having incest in mind as you put it, it just feels like the developer put it in for the appeal to that side of the player base and not for the sake of the story when the story of a visual novel is literally the most important element of that game type. As for the extra work, you forgot he also has to patch it out for Patreon and that's assuming Patreon hasn't started cracking down on patches.
Question is it not Caribdis the leaker I know they are the creator I thought they were also uploading as well though ?
When the public release comes, they do. There's no way Caribdis is leaking his own patron only builds, that defeats the whole point of having them be patron only.