There is nothing in your post that indicates what the custom data types might be or what formatting is required.



For the conditional line output, see Mailmerge Empty Line Suppression in the Mailmerge Tips & Tricks 'Sticky' thread at the top of this forum: https://www.msofficeforums.com/mail-...ps-tricks.html

No VBA needed for this.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]

I have a merge field in a tab delimited csv file that is of the format ["element 1", "element2"] from 0 to 12 elements.

What other information is required?

An example of the field in the csv would be <field separator tab>["element 1", "element2"]<field separator tab>

The VB function takes that data and format it into a multi line string but I now need to call that function and display that result in the merged document.

CSV files have Comma-Separated Values. A tab-delimited file is not a CSV file, no matter what extension you give it.
Evidently, then, you data are coming from some other system. You should get whoever produces the data to output in a format that is suitable for mailmerge. Alternatively, pre-process that data so it's suitable for mailmerge. That would require all 12 elements to be catered for in each record, even if empty.

Your ["element 1", "element2"], etc. do not constitute custom data types - in a tab-delimited file they are a single piece of data and, with the double-quotes, are liable to mess up a mailmerge.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]