You'll be fine, Inbreeding goes back 3 generations including the generation of the kid
Compare the parents and grandparents of the pets you want to breed, if they're's no overlap, there won't be degen in the kid. You have:
C1:
Parents = B1, C
Grandparents =A1, B
A:
Nobody
No overlaps there. And so the kid will have the no degen. Its lineage will have A, C1|B1, C|A1, B. With '|' seperating the generations that get counted.
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In action (Check the profile of my pets for a list of their parents and grandparents): B1, A
Those two are kind of in the position of your B1 and A pets. They can't breed with each other because they're both related to Shamrock. Shamrock is B1's grandparent and A's parent. B1 breeds with someone unrelated to get C1. Shamrock is C1's greatgrandparent, but it doesn't matter since we only look at the parent and grandparents. C1 breeds with A and makes a baby without degen.
Recent progress: Project Perfect