Banalne pytanko

"Unless they had sold the house, they wouldn't have so much money"
To zdanie jest w dziale 3rd conditional. Co mnie dziwi to drugi człon zdania, dlaczego nie "wouldn't have had" skoro to 3rd conditional, a nie mieszany?

If they hadn't sold the house, they wouldn't have so much money. --> Gdyby nie sprzedali domu (jakiś czas temu, w przeszłości), to (teraz) nie mieliby tyle pieniędzy. [Dobrze rozumuję?] (ale sprzedali i mają)

If they hadn't sold the house, they wouldn't have had so much money. --> Gdyby nie sprzedali domu, nie mieliby tylu pieniędzy (ale sprzedali i mieli)

przede wszystkim 'unless' nie mozna uzyc w tym zdaniu

if they hadn't ... they wouldn't have = mixed conditional 3+2
if they hadn't ... they wouldn't have had = 3rd conditional

Wouldn't "Unless they had sold the house, they wouldn't have so much money" be OK in the context of deduction as regards something that happened in the past?
i.e. someone's got money and you don't know where it's from. So you try to work it out based on evidence/events that occurred in the past. I'm pretty sure that would justify the sentence and the use of unless.
But it's late, Saturday evening, and I've had a beer - I might be wrong.

deduction doesn't need conditional tenses, at least in the CAUSE part.

'Unless they (have) sold the house, they wouldn't have so much money'

my 3 eurocents