I worked in chrome plating for many many years.
1, you can drill your hole etc
2, send the bridge plate to the chroming company. Here they will strip existing plating back to the bare metal
3, They will probably need to re-polish the metal (we would have), so that the visible surfaces are free from any marks, pitting etc
4, Then they will re-chrome. They may put a light coating of copper first (sometimes we did, sometimes we didn't) then nickel then the chrome top coat.
Much of the work involved is in the polishing of the stripped metal.
Sometimes we would increase the price because you just know a particular job is going to be a nightmare (some jobs are, some customers are)
We still have some chrome/ nickel/ zinc plating done where I work (we shut our plating shop 18 years ago. It was a health and safety nightmare and becoming harder every day)
We use a company called Butterworths, based in Ramsgate. They could probably re-do your bridge. We would have charged a minimum price, which was £25 plus vat. (if, however it was someone I knew/ liked it would have been free)