To confirm the registration of an Australian native hybrid & view its composition/progeny: (Database as at 1st April 2018 RHS registrations)
For non-Australian Dendrobium hybrids use the Dendrobium Hybrids checklist here
Sarco. Heartfelt= Colonial Hart x hartmannii registered: 16/03/2017 by Butler D.F.
Species composition summary:
Sarco. Heartfelt = Colonial Hart x hartmannii = [serrulatus x Fitzhart] x hartmannii
Fitzhart = hartmannii x fitzgeraldii