In a joint partnership agreement have to be made, which might be OK without a verbal contract is proof of it. But if you make a written contract in order to prevent disputes later on, it can be done.
To establish joint partnerships It must be made clear to the agreement. This could be agreed verbally Without any written evidence. The book will be written. To prevent disputes later on, it can be done.
In establishing the partnership. Have to do an agreement clearly, which can deal with speech. Without the evidence. But if you can start a contract in writing. To prevent some arguments later, it can be done.