This thing is being programmed thru smart contract. If I were you, simply forget about this idea because both transaction will eat up gas fee. Simply talk to your partner and set up a day cut off, and simply divide the money base from the transaction. Just try to imagine how much gas fee it will eat up if everytime it will send to both addresses.
I am new to bitcoin technology, I want to build Altcoin payment button with 2 bitcoin addresses, first is my site address where I will receive a small commission fee, second is my site seller address. When a customer pay, bitcoins will be send to both addresses, is that possible? Thanks