water hammer after whole house copper repipe
If the supply valves for the sink (farthest away) are screwed onto a stub of the copper pipe with a male adapter (they should be), then you can simply put in a tee on that pipe, a close nipple to re-attach your supply valve, and in the top of the tee, facing up, install an arrester or even just a piece of pipe with cap on the end to trap air in it.