Regarding naming the new bridge: Here is a way out of the controversy. Rename the Poplar Street Bridge the Stan Musial Memorial Bridge. Name the new bridge the Veterans Memorial Bridge.
Rational: I understand that the poplar Street Bridge was never given an official name and it runs right by Busch Stadium, so it's appropriate for it to be named after the greatest Cardinal of all. I don't believe anyone has a vested interest in the Poplar name.
The new bridge then could be named the Veterans Memorial Bridge as that was the original name of the bridge that was changed to the Martin Luther King Bridge. This probably would be supported by both states and everyone concerned.