Patch, I've used search function but no luck finding my problem

I have multi copies of wow installed as I have 3 accounts & different Ui setups for my 3 different accounts (I find this handy when it comes to all the custom Ui tweaks I do to each different account/character)

Now I have succesfully patched ONE account but the others are having various patch errors that have been mentioned by others. I can remedy the error by del wtf, interface, patch.mpq & downgrading wow then running repair facility etc etc. HOWEVER this then means a complete rebuild of the Ui's and macros for the other installs on the machine.

SURELY there is a way to fix the patching issues I am having on the other accounts without having to wope the Interface, WTF and interface folders?

Here are three posts I found, Hope one of them helps you :)

Multiple WoW's+patch AND YOU!?
[Solution] Problems patching multiple WoW client installs (Vista)
How to patch

(Note, the search function on the site can be wonky sometimes, for best results, use google. For example google this: site:dual-boxing.com patch )