I guess Zara and Vanessa to become guaranteed LI, this would imply a bit of fiddling, especially if Nojiko and their father get together for real, it's not literal incest, but Patreon doesn't seem to understand the difference. But they both sure have an interest for the MC, Zara especially if the MC is fit enough to win the game with her (don't see why someone wouldn't be fit at that point, perhaps to try I guess), Vanessa like you said has her own agenda, she's haughty and snob, but seems it's all a game with her, a state-of-the-art femme fatale... but since the MC is a player, too... and yeah, Nami could be toyed with, it will trigger the MC. Mario is a puppet she's using, cause yeah, she doesn't need his money, for sure.
Pure speculation, but I love speculating on open-ended games like this one.