Many years ago I went to work with a man who was looking for a young man to train and take over the business. I was made promises and given a price to purchase the balance of the business and he was going to allow my work to earn 25%. A few years later, he re-married, hired the low life lazy step daughter who told me that it would all be hers one day. When I confronted the man, he simply stated, if I had the money I could buy the business, his wife wanted the step daughter to take it over. I was out and moved 600 miles to start over, ended up getting about 10 cents on the dollar for the stock I owned. Unless you own 51% of a privately held company you are SOL plus at some point, the son will be a 75% owner and your share will be worthless. There are always exceptions, so if the wage is good for you just do it and take the risk. Get a contract if you can, but remember, blood is thicket than water. How much would you need to make the deal on the nursery and go it alone?
My wife said "you're on lawn toy restriction"