I need it to return a payment to one of the sending addresses.
No!
No, no, no.
Just no.
In Bitcoin, there's no such thing as a "sending address". DO NOT try to guess at a return address from the inputs of a transaction. Doing so WILL eventually result in lost bitcoins and angry users. If you want to send bitcoins to someone, ASK THEM TO PROVIDE a receiving address, then use the address they give you.
There are just SO MANY ways that guessing a user's address from inputs will result in you using an incorrect address.
Yep one simple way is someone pays with coinbase.
The address that pays has nothing to do with the senders coinbase address.
The coins come from coinbase’s hot wallet address not from my coinbase address