Second should be father and daughter, since Daiwa Scarlet was a female horse IRL.
Fixed.
父子 usually means "father and son", but since it technically means 'father and child", it can also refer to a "father and daughter" pair.
Side note, easiest way to check (without looking up the actual horse) is to look at the ear accessories. Or hair accessories near the ear. Stallions have eardecs on their right ears (or hairdecs near their right ears), while mares get them on the left. Bit tricky in the case of TM Opera O, but her crown is tilted to the right.
