I have this tephrosa at my house, and so far.... It defies my efforts to propagate.
It produces seed, but most are eaten by weevils.
When I was able to find viable seed, they came up readily... In pots.
When the plants were set out, the voles killed the babies. The ground planted seeds? Reckon also vole casualties.
Over in NC at King's Mountain.... Dunno if it's even legal for you to collect seed... But if you can.... Y'all may have less pests than I do.
Incidentally, I also have the wild Sandhills threadleaf coreopsis, and attempting to move it into the garden just feeds the voles.... I can't even grow jeruseleum artichoke!