Identify faucet model and access

[joat]

I am trying to service this bathtub faucet in a 1980s-era condo. I believe there is a shut-off valve behind the backplate. I cannot identify the model (other fittings appear to be Kohler but I can't find this model on their website). In particular, I cannot figure out how to access the backplate (without the need to shut off the main water line which would require shutting off water to multiple units on multiple floors).

Much gratitude for any help and suggestions!