I recall seeing something about dragons of close blood not able to breed. However, I put the brother down and a dragon to preview their babies and when I went to switch the female dragon, the sister was unlocked to breed with the brother. This also applies to father breeding with daughter, mother with son, etc. I don't confirm this pair because I believe it's against the rules and of personal history. That's what I found.
TOPIC | Breed Glitch
I recall seeing something about dragons of close blood not able to breed. However, I put the brother down and a dragon to preview their babies and when I went to switch the female dragon, the sister was unlocked to breed with the brother. This also applies to father breeding with daughter, mother with son, etc. I don't confirm this pair because I believe it's against the rules and of personal history. That's what I found.