If the horses are what you both say they are and could possibly be, I'm wondering about pearl. Pearl is currently only known to be in Paints, QHs, Andalusians, Lusitanos, and Peruvian Pasos and is relatively rare, which is why I'm hesitant to say it because I can't find anything about it possibly being in TWHs.
Pearl is a dilution that is a bit strange in that one copy doesn't show up on black, chestnut, bay, or brown. But 2 copies make an apricot-like color. Howeverr, what makes it different is that 1 copy of pearl plus 1 copy of cream ends up with a pseudo-double cream looking color.
In this case, the pearl gene would most likely come from the apparently chestnut dam and the sire would have to be smoky black like previously considered.
Wayyy out on a limb, but the gene is testable at UC Davis. It would be very interesting if it were to come up positive for pearl though, but that's me with my optimistic pants on.