[BB_TX]

Don't remember the models but some have found the valve under the lavatory. Since you said it leaks on the curb side and the shower is on the street side I would question whether the valve is behind the shower.
On mine (different model) it was behind the shower. Mine also was dripping off pipes in the basement. But there were four water lines there. Mine was behind the shower, but the shower only needed two water lines, hot and cold. So I knew the two extra ones had to be for the flush valve. See if you can determine that there are two extra water lines in the leak area on yours.