We don’t track horses in the herd:
You can choose vanilla, where you can draw up to 4 war ponies
You can choose my houserules, where you can draw £40 worth of horses - and of the war horses, these are:
Rouncy - £1
War Pony - £15
Courser - £10
Charger - £20
If you want more, you can pay for more by devaluing the herd. Any knight in your household not given a War Pony, Charger or Courser (family excepted) will leave your service and fine a vacancy elsewhere - it’s a renters market with so many free spaces.
You sold the horses early because you wanted to spend the money, imagining your destrier was unlikely to die, unfortunately because Dice were rolled I cannot let that be retconned.
EDIT: I got my sums wrong, you can spend £40, not £32 if you want to use my house rules