1031 Exchange through a family owned property

[Camden Smith]

My dad has 4 duplexes. I want to buy 2 or maybe all of them. He wants to role the sale proceeds into a 1031 exchange. Is this legal to have a family member buy your properties.
Also... my Dad would also be "the bank" for the purchase of 2 duplexes-- let's say. So he would fund the total amount minus my down payment.
What are the legal ways to do this so that I can buy 2 properties from him, he can sell them, and still use those sale proceeds (along with the sale of the other two duplexes) into a 1031 exchange into a commercial retail property?