It doesn't appear to be possible. You would need to nest both the prefix and seq field but the Seq field double counts even when one is not visible (so the table numbers double each time. For instance, the following looked promising

Table {If{StyleRef "Heading 6" \p} = below "{StyleRef \s 1 \n \# "0."}" "{StyleRef \s 6 \n}"}{If{StyleRef "Heading 6" \p} = below "{Seq Table \s 1}" "{Seq Table \s 6}"}

Even if you could get it to work, it would require additional constructions to deal with either Heading 1 or 6 not being numbered OR not being present in the document.

I think you are going to need a macro to do your captions and deal with all the variables you have asked for. Such a macro would be possible but the variations make it complex.

Why don't you just setup each of the caption variants you want and save them as quickparts and then insert the relevant one wherever it is needed?

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Andrew Lockton
Chrysalis Design, Melbourne Australia