What I do for exchanging money between characters:
I've created Gold Piece, Silver Piece, Copper Piece, and Platinum Piece items under Gear in the Editor, with the appropriate weight and value. I "buy" them using the character's wealth, then I can transfer them as needed from character to character.
Or, since my players are a bit paranoid, I can stash some in a secret pocket, leave some in a belt pouch, put some in a bank, and so on.
You could go into the Editor and create a "Loan" type of gear. That will tie up the money for the lender, and it probably should still count against his Wealth because he is due to get the money back... he just can't liquidate it until that happens.