Replacing faucet copper pipes with stainless steel, need help
All you need to do is gets the appropriate tee for the job. 

This tee allows you to connect two compression output to one input



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Turn off the water and open the taps. 
Unscrew the copper and gently bend it to allow space for the tee. 
Attach the tee and connect the copper to the tee at the most convenient branch. 
Attach the braided stainless to the other branch. 
Open the valves, check for leaks, close the taps, check for leaks and done!