"It's fairly industry standard. For mortal purebred sale and adoption contracts, generally a clause would indicate the requirement to sterilize and not breed further from any purchased stock. It protects the sanctity of the lines from dilution. However, with animals touched by fae ancestry, you see that it is less straightforward. One may even say, rude to imply.
Right of first refusal means that should you choose to breed from Silverwolf stock, our stables would have the right to purchase any such foals, rather than them being sold, bartered, or traded and henceforth their lineage untraceable. In effect, if we were to disprove of a sale, it could be overruled by our right to purchase back the litter or foal in question. Again, as you say - mayhaps not a concern with one of such unquestionable morals as the Dame herself, or Rivervale's reputation.
In any case, this would grant such permission, should he choose to enforce it, over to her squire - and to her, given his Minor status. Thus freeing Silverwolf of future obligation to the line."
A small sigh. "Thúl-o-mithril is my most promising mare, but I have been uncertain about breeding her further. I am loathe to see the line end. In that, I'm glad that Tinuoroch is gravid, and would be interested in seeing how she foals. Not a proprietary interest, mind you - just, mm... familial, I suppose it would be."