Word has a range of such tools, but I can't see how what you're asking about has any necessary connection with a mailmerge.

As for possible solutions to your problem as stated, you could use a FILLIN field - to insert data just at that location - or an ASK field - to use cross-references that replicate the data in multiple locations. See: https://support.office.com/en-us/art...rs=en-US&ad=US

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