Due to the complexities involved, this is currently scheduled for the next rewrite of the UBBCode parser, which is probably due no earlier than 6.4.
In the mean time, there has to be at least a few workarounds you can try...
Have you tried multiple lists? Or just HTML lists?
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Charles Capps
Programmer, Infopop Corporation
Please do not contact me privately for support - post on the board or open a support ticket instead!