I got some fry summer 2019, and I have not paid so much attention to them until today when I found that the only asagi among them has got kado ginrin on 20% of its scales. I did notice it 3 months ago. Today it is about 15 cm long.
It is from a flock spawn, and among the koi that participated there were male sanke, male yellow matsuba, male ochiba and a special type of ochiba (female) which is yellow/white and metallic (I forgot the name).
So I also wonder if it can be the fry of the two ochibas?
I am not sure about the ginrin aspect of your question. Though I suspect it can happen, I have never seen ginrin from spawns that did not involve ginrin adults. Perhaps the matsuba is one of the parents, as I believe matsuba and asagi are closely related.