To confirm the registration of an Australian native hybrid & view its composition/progeny: (Database as at 1st January 2020 RHS registrations)
For non-Australian Dendrobium hybrids use the Dendrobium Hybrids checklist here
Sarco. Billie= Weinhart x First Light registered: 28/10/2005 by Roper N.
Species composition summary:
hartmannii 62.5% weinthalii 25.% dilatatus 12.5%
Sarco. Billie = Weinhart x First Light = [hartmannii x weinthalii] x [Aussie Dawn x hartmannii]
Aussie Dawn = hartmannii x dilatatus