Assignment w/o Seller Approval

[Blake Alexander]

Hey BP! 

I'm a real estate agent in Los Angeles and I'm working with some flip clients. They want to know if they can assign their contract (for wholesaling purposes) in escrow without the seller's approval of the assignee. 

Other agents I talk so say you need the seller's approval, others say they've never heard this question before. I'm new to working with flippers and don't want to mess this up. 

Any thoughts? Thanks!