I know the dam is a registered arab derivative, just don't know her name (arab derivative can mean anything but is most commonly TB, Warmblood, Australian Riding Pony or Welsh in addition to the Arab blood). I know the type of the sire and I know my girl is strongly looking like maturing a lot like him. I also know a few really nice Welsh Ds that would cross well with my girl if she does mature to look like her sire.
I may not know the exact breeding of the stallion, but he throws a very consistent type (I have seen several of his foals) and I know what type crosses best WITH that type.
A horse is most likely to throw back to its parents in its offspring, so if you know the parents of a horse you know what it's most likely to throw. It's quite often seen in Thoroughbreds, if you look at the best racehorses their parents might not be champions but their grandparents quite often are.