OK, got it. I didn't really know anything about mycoplasma, so looked it up on other forums. And I learned that not only can it be transferred from bird to bird but ALSO transovarian (transmitted into eggs that are laid). Thus your caution about new chicks is indeed well founded. I am grateful I've been lucky with my tiny flock in spite of not knowing all this.
Anyway, good luck with your upcoming order.....let us know how it goes.
Anyway, good luck with your upcoming order.....let us know how it goes.