Need help with deck-randomisation

Hello, long-ish time user, first time poster here. So I've got a problem for an upcoming set of boardgames I'm gonna run. The situation is as follows. I got 2 decks. Deck 1 contains normal cards. Deck 2 contains higher value cards. I need to mix set numbers from each into a third deck that I then shuffle, without knowing what cards are in this new deck. I've yet to find any real solution to this. I tried actually just putting all the cards on the tabletop and shuffling them by hand until I could no longer remember which card was which, but the problem with this is that the first drawn card will stay below all others layer-wise, thus making it obvious which cards are which etc... I hope I've clarified my issue. Does anyone know a way to solve this, or maybe if there's a function that lets every card i click on get put on the top layer?

Unfotunately the function you described is not available. (Maybe  Suggestion worthy?) Have you tried creating a new custom deck for the third deck? Since the third deck has set cards couldn't you just make it separately? If that doesn't help, you might share the game type so we can try to better understand. :)

The problem with creating a third deck is that I would have to know what cards to put in, which should be secret to all players, even me. Only the number of cards from each deck is set, not what actual cards are used. I've however looked into some other solutions that will have to do, thanks for your time.

Thanks Jakob B. - if you get a chance let us know what you ended up doing to get it to work. That way other users can learn from your work!

It wasn't anything spectacular, I'll just manage by shuffling a proxy deck IRL and people will just have to trust me, upon closer inspection I realized there was already a suggestion for what I needed, so ill just deal with it like this until the suggestion becomes reality. =)