I'm thinking that the frames are custom, they have to be. Seeing you have to contact ESP before sending the card would it be unreasonable to ask if they could do the jersey in the frame WITHOUT including the cards?? Seeing it takes so long to get the frames back I'm assuming they don't have them all on hand, framed and just waiting on the redemption cards to arrive.
Maybe the owners can actually have a say in how the jersey and cards are presented?? Can't hurt to ask.
Just to take Missing Hinges comment a little further, and in the event that the cards could be separated from the frame, then would the cards LOSE any value if the frame wasn't to remain with them?