MS Access SQL - Count number of unique values per file name

Question

My table looks like this:

File_Name	Full_Name
Hill, Hank	Peggy Hill
Hill, Hank	Bobby Hill
Gribble, Dale	Nancy Gribble
Gribble, Dale	Joseph Gribble
Gribble, Dale	John Redcorn

I'm trying to make a query to do is this:

File_Name	Full_Name	Relative_Number
Hill, Hank	Peggy Hill	Relative_1
Hill, Hank	Booby Hill	Relative_2
Gribble, Dale	Nancy Gribble	Relative_1
Gribble, Dale	Joseph Gribble	Relative_2
Gribble, Dale	John Redcorn	Relative_3

I want to then take the number of Relatives and use it in a CrossTab query for my MailMerge. Can anyone help?

I'm about to count the total number of relatives per file, but I can't assign a number for each one that starts over per file.