Recommended way to share property ownership?

[James Wierzba]

I own a few long term rental properties. The titles are held by a sole proprietorship LLC for which I am a 100% owner. ( the LLC does not have a tax ID, i use my SSN)

My brother is investing with me now. He has paid me 50% of the initial down payment and we now consider him to have 50% ownership of the property.

Currently , it is an informal agreement ( nothing is in writing). We want to formalize it just in case of future disagreements. 

Question: what is the ideal way for us to officially record that my brother owns half of each rental property? Is it possible to have him own half of each title ? Or should I give him half ownership of the LLC?

Disclaimer: I plan to consult a lawyer but I just want to get some initial thoughts from experienced investors here.