Why didn't you just have your brother log in? Also, coin dropping is blocked by the UI so I'm not sure if they'll ever be able to fix that into classicness.
If you want to transfer plat, just buy some gems. You'll lose a small bit on the conversion but if you're transfering more than a few hundred PP to be able to buy spells with you really should just find someone else to do it for you.
Now, I am with you, I'd love for either shared banks or the ability to create a 'transfer' account that you could 2 box with legitimately but it's never going to happen. Infact I even made a poll about it a few years ago:
http://www.project1999.com/forums/sh...ad.php?t=36316.
It won't happen so I've just learned to adapt.