i still think
@CedSense can still make a harem in the love route, simply making the mc going to that other woman he likes besides the D and tell her he loves her too but also want to be with D. I really think a love route with D and Melinda is possible after all she helps the mc in the other path, and grace,susan or other girls i think can also work out if done correctly after all they kinda love the mc, as for anna she loves the daughter so... there is many ways the dev can make this game and it can also be realistic, no need to go the dark path to have a harem route or be a douchebag.
let me give you an example for grace:
(after the mc tells grace off, the daughter sees grace while shoping for clothes, they talk and the daughter ask her if she really loves the mc, grace tell her she really love him, since the daughter is such a kind and good girl ask her if she wont mind sharing the mc if the mc agrees....then after this, they just talk to the mc what he thinks about it etc, kinda simple if you ask me)