Tony knew enough about transferring funds given his own allowance as heir and being privy to all of the things Harry handled with his two lordships. The Potters had kept everything within two vaults but the Black accounts had multiple vaults that Harry was trying to wrangle into one. While it sounded easy in theory, Harry couldn’t simply transfer the funds and close the vaults. No he had to do it in transactions and even currency exchanges which had their own restrictions. The Blacks didn’t just have vaults in England, no they were paranoid and had vaults in branches across Europe and transferring funds to another country always created problems. The goblins weren’t willing to just move money. Oh no... they had to make a profit somehow.