Billy Ray Cyrus can't stop, won't stop ... cranking out talented spawn -- he performed live with Miley Cyrus' kid sister in L.A., and it sounds like the family's got a new revenue stream coming.
Noah Cyrus jumped on stage for open mic night at Crave Café … and Billy Ray backed her up on guitar for a few songs. It was no sold out stadium ... but hey, even Miley started somewhere.
The 15-year-old -- who sounds a lot like big sis -- belted out her take on one of Dad's hits ... "Could've Been Me.”
Watch ... for the singing, and Billy Ray's gushing afterward. He should be happy -- with such talented kids ... he's all setup for one sweeeet nursing home.