Buyer transferring llcs after sale on land contract

[Alex Martin]

I sold a portfolio of rentals a couple months ago on land contract to an individual who formed an llc to hold the portfolio.  He is now looking to partner with someone on these and is asking to transfer the properties. The new llc he wishes to move them into already has a large number of properties in it and also has the new guy named as partial owner. 

I'm not looking to be difficult for no reason but I'm hesistant to give the thumbs up to transfer stuff. I technically agreed to sell to guy #1, not the new guy. I'm wondering if doing so would open me up to any additional risk as well? Since right now my properties are held by a single member and are the only properties in the llc. If they transfer now I've got multiple people in the llc and a large number of other properties as well. Thoughts?