The red flag was working with family + business. Those two things just don't mix especially if you already have a bad foundation and more money isn't going to solve it, it will just increase tensions. I don't get my family involved in my side gigs and would like to keep it that way to prevent any sour relationships from not getting what I/They want from greed. I hope you consider trying a different path if feasible or if it's in the same business, just a section where you're free to do your stuff and left unbothered by the main branch.