Hello and welcome. Thank you for providing an opportunity to assist you.
All you need to do is to have a proper SALE / PURCHASE of LLC Interest Agreement. Such documents are standard in nature. The following two are very good example of this.
IN ADDITION this, if you are purchasing an interest in a start up company, you will need to have an "EXIT CLAUSE" in place. Exit Clause details HOW you will liquidate your interest in the LLC when it appreciates in value. Such exits are usually done when the company lists OR finds an alternate investor. FURTHER, you will need to detail the EXTENT of your managerial involvement in the company. By this I mean, you will need to be very specific if you would just be and investor OR will have a seat on the board OR will have any involvement in the day-to-day management of the company.
So, "Exit Clause" and the "Participation in Management, if any" are the TWO ADDITIONAL things that you will have to include in the above sample agreements.
Apart from these, there are no specific documents that you require.
I am sure this would help.
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