patreon is perfectly fine as long its not incest directly ( by family relation or function of the chars)
the simple fact to not use "mother" and "sister" and else family relative function to an char fix the problem perfectly.
even if , in a story way, its kind of obvious its family relative.
as exempl, you can make a story saying MC have sex with landlady or "miss piou piou" and in the story make MC living in same house as this lady, even if the lady act like if she was a mother of MC as long its not clearly mentionned, then its fine.
thats why "landlady" ( wich i think its ridiculous and lore breaking, would prefer to name her like "Ms Something" instead ) is used to replace "mother" and "roommate" for "sister". story stay the same, but they are no link to be family relative between MC and thoses girls, and so its fine for patreon.