Do not enter into a contract with an employee that limits your ability to terminate them or change their comp.
This is a major concern for me. If at some point I'm not satisfied with the performance of the grower and/or manager, my ability to fire them is hampered by the fact that they're officially part owners of the business-- they're not merely employees.
Let's try thinking about this a different way. Set aside the legal concerns, and the fact that your bother is involved (family ties usually muddle objective analysis). Random Stranger approaches you with a business opportunity in industry X:
Random Stranger: "Industry X is ON FIRE right now! I have an incredible opportunity for you to get in on the ground floor. You need to strike while the iron is hot, don't let this once in a lifetime opportunity pass you by."
You: "Uh, ok. Tell me more."
Random Stranger: "We have a plan, and some people, and maybe some properties lined up. But we need capital to get started. That's where you come in."
You: "How much are we talking about here?"
Random Stranger: "We need $350k to get things off the ground."
You: "Uh, ok. So I would invest $350k in your business. What do I get in return?"
Random Stranger: "You get 50% ownership."
You: "I see. Is this business a going concern?"
Random Stranger: "No, we haven't incorporated or anything like that. That's why we need funds to get it started."
You: "So no inventory, no product, no customers?"
Random Stranger: "Correct"
You: "Do you have any of the required permits or regulatory requirements?"
Random Stranger: "No"
You: "So, um, what exactly would I be investing in?"
Random Stranger: "A great idea. And 'human capital' - there are three of us. One is an expert in producing the product. Another is good at business stuff. The third guy, well, we don't quite know what he will do yet as he has a history that limits what he can do in X. But he's super motivated, so there's that.
You: "..."
Random Stranger: "Oh, and because of some, uh, reasons we're going to need you to be the legitimate face of the business."
Let's think about this. How much is a business idea worth? Approximately $0. This is not a going concern, so there's no value in customers, supply chain, distribution channels, or anything. The business doesn't actually exist outside of the imagination of a few people. The business valuation is approximately $0. You're being asked to "invest" $350k, which means, after your investment, the company will be worth $0+$350k=$350k. However, you only get 50% ownership, so in effect you transferred $175k to these strangers. Don't be fooled, no matter how much they try to convince you that you retain full ownership of your initial investment, it doesn't work this way. If the entity (if it actually existed) were dissolved tomorrow its assets would be split 50/50 between the owners. The only reasonable amount to invest in a company worth $0 is $0. If it was already a going concern, and an independent appraisal valued it at $350k, then a $350k investment in exchange for 50% ownership could make sense (assuming everything else checks out and you think it's a good investment).
Give that, the only reasonable response to this "opportunity" is:
You: "Get off my property or I'm callin' the cops!"
Now, since this is your brother, you can be nice about it. But whatever you do, run far far away from this. You are already on a path to FIRE, this is guaranteed to derail the trajectory you're already on.
One final thing: It's worth asking what your brother brings to the table from the POV of the manager and grower. They both have skills (presumably), so why are they willing to give your brother a cut of the action, and at a percentage almost triple their own? The most likely answer is that he's your brother, he has connections to family members with money. He is being used to pull you and your parents into this scam.