So when naming your model change MPQs

[Sorrow23]

3-9 and a-z work?

As in patch-3.MPQ

Or patch-w.MPQ

I've run out of numbers so I'm wondering which letters work.

[Squirr3l]

I'm not sure on the letters either, so I'll keep an eye out.
But I've always assumed you can just keep adding files to your first archive you made with MyWarcraftStudio....

I've got over 30 .blp files in just one .MPQ, patch-5, the first .MPQ I created.
Just a thought, If im wrong, im sorry, if not...well then, you have more space than you thought, eh?

[Dragon[Sky]]

All letters a-z work.
As for numbers, 3-9.