Although it is possible in real life business that you can work on partnership with someone but this is not what they do in reality. In reality most of these "managed" accounts actually go "mismanaged" because they are not backed by any legal paperwork.
People tend to give their account username and password to someone just because he got a good looking website and is promising huge profits in short time. As a result, soon after these people hand over their password to someone, their accounts get empty. Also the nature of Forex business is such that no one can manage someone else's account, no matter how sincere he is. Sometimes you really have to make tough decisions and these decisions can result in big losses which the account owner might not approve (especially if he/she is new to Forex). So it is always better to trade yourself in your account.
Solution to the problem: