You need two different outline numbering streams to be able to re-combine the lists but allow them to retain their separate formatting. Your description makes it sound like both streams had the same origin and then you altered attributes.

Without knowing your level of understanding of outline lists I'm not sure this will make any sense but I think you need to create a different name for the outline list in each document. If this means nothing to you, then perhaps you should attach a couple of sample documents showing both lists as you want them formatted. Leave space in one for the other content to be pasted so we can work out the simple way to describe what you need to do.

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Andrew Lockton
Chrysalis Design, Melbourne Australia