You do realize the answers to many of those questions aren't even answered by the game as-is? The family already could easily move away especially since a majority of them dislikes Hunter from the very beginning. And the question of how Brenna makes money is ALREADY and issue in the game that it just doesn't address and pretends the mom doesn't know anything. It wouldn't change either way.Lets pretende Hunter became a "shadow agency", why they would help Ophelia and family? Why Ophelia would accept some random peoples help? When they start filling weird, why they wouldt move away? Even the whole sex stuff wouldnt make any sense since MC fuck every one because hes trying to stop Hunter, and MC money comes from sex scenes with Breanna, if him just appears with a bunch of cash out of nowhere, Ophelia would ask how he got that, and they live together, Ophelia knows MC dont have a job, and if you play with NTR On, you just see the consequences of MC mistakes but if you are not blind by anger against Hunter, you can see hes essential to the plot with NTR Off.
As for the rest such an organization could easily fool Ophelia into thinking she's accepting help from someone she knows, or from the government or something. Easy. And the MC would do the exact same things he's doing to try and stop the org.
No, he simply isn't essential. He does nothing in "NTR off" mode that can't be explained just as well in a million other ways.