I think it would be vital to the company's survival that roles and responsibilities are clearly defined. If there's grey area, I've found that work tends to gravitate toward the more motivated party, and the social/power structure gets weird.

I started a company with four founders, and we didn't define roles. What ended up happening is one person didn't do anything that wasn't interesting to them, one person would start a bunch of tasks and leave them half-finished for someone else to handle, and one person was only capable of handling process-based work, which left the fourth person (me) to handle everything else (and write the processes).

It bred resentment and made it very difficult to adjust roles going forward, because it had been established that I could do everything and therefore I became the final point of responsibility, even if we'd defined new roles later. Our only way out was to sell the company.

In later companies, I laid out responsibilities clearly and made sure each founder had ultimate responsibility and autonomy around their tasks. This has worked out FAR better in every case.

I've built a framework that I use for defining and divvying up tasks, and it's made a huge difference. I've had my coaching clients use it as well to similar results.

If you need a fresh set of eyes on it, or if you'd like to bounce ideas, I'd be happy to talk. Drop me a request and we'll talk.

Good luck!