I am creating a letter to many suppliers to communicate
that PO numbers have changed. The supplier may have many
POs open, so the letter should include all old PO numbers
and all new corresponding PO numbers. The data looks
something like this.

Supplier Old PO New PO
Supplier A 43002 99001
Supplier A 43009 99002
Supplier A 43011 99006
Supplier B 43016 99007
Supplier C 43020 99009
Supplier C 43025 99012

Does anyone know how I can use mail merge to put the first
three records into one letter to Supplier A, put the next
two records into one letter to Supplier B, and put the
next two records into one letter to Supplier C? Basically,
I want each supplier to only get one letter from me which
lists all their POs.  I need mail merge to understand to
group records in my Excel data sheet by the vendor number.

Please help!

Thank you,
Jeanie