Hi FoxFX! Thank you for purchasing the project.
You could achieve that by making an object which stores the list of the IDs of the cards you have in a ds_list (myCards). The you can create another ds_list called myDeck and through that object you can move the cards IDs from the myCards list to the myDeck list.
Remember to always use cards IDs in the lists and not the card instance IDs or whatever.
For example, this is what the lists should look like:
myCards = ["001", "002", "003", "005", "007", "010", "024", ...]
myDeck = ["001", "005", "007", "010", ...]