Has anyone ever hired a owner operator for contract work? How did you do it?

My friend has a trucking company, she's just a one truck operation right now with her box truck and she has a contract that she does in her truck!

However, she got offered a contract with a "CONTRACTOR" it's not a DIRECT contract, meaning she's working with a company that has the direct contract with the supplier... It's LOCAL work, and no MC required. The route pays $315 a day. She wants to hire on an owner operator with their own truck, and hire them on as independent contractors and pay them $6200 a month for this route.

She currently has commercial insurance for her truck, she has an MC USDOT all in good standing... Are there any thing she would be required to secure before hiring an owner operator? In terms of legal and insurance type stuff.

P.S Background checks and drug test will be conducted prior to signing them on.