What character changes did he make? I haven't heard about this before, so if you could enlighten me, that'd be appreciated!
Noticed I got the name of the story wrong - it's "Font of Fertility".
Originally the MC was in a relationship with his girlfriend, his older sister and his girlfriend's older sister (with everyone in MC's harem sleeping with each other).
In
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this was changed so the GF and her sister were then step-sisters by marriage, and the MC's sister turned into his godsister, who his parents took in when her parents died earlier.
Since this was obviously not enough for Patreon, it was further changed in
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, where the GF's sister is now just a former neighbor of the gf, while the MC's sister is now only a family friend.
The author apparently also didn't consider enough on how it would change the story - e.g. the GF's sister had a bad reputation in school, and in chapter 34 the GF now faced some repercussions because of her last name - which should be different as they're not even related anymore.