Update query based on SOUNDEX results

[Mickey Mouse]

My MySql experience is limited to simple updates and selects. I am
creating a genealogical site based on Old Church birth and christening
records. Currently I have over 70,000 entries in the database and I
want to link the parents together in order to see all their children.
Currently I have the following fields FatherGiven, FatherLastName,
MotherGiven, MotherLastName and I want to create a field called FRN
which if the Soundex of each of these fields stayed the same would
stay the same but would increment by one for the next Family

eg.
FatherGiven, FatherLastName, MotherGiven, MotherLastName, FRN
John, Smith, Jane, Doe, 1
John, Smyth, Jean, Doe, 1
James, Smith, Mary, Doe, 2

Etc

I can already do a Select statement that puts them in the correct
order but I have a hard time figuring out a Update statement that is
going to go through and check and create the FRN number.

Can anyone help me?

Thanks