I'm sure you could create a variable that combines the current date and the "Alpha" in the correct format corresponding with the filename and then imports that file into filemaker.
Create a variable like:
"Alpha" & "_" & Month ( Get ( CurrentDate ) ) & Day ( Get ( CurrentDate ) ) & "A" & ( Right ( Year ( Get (CurrentDate)) ; 2 ) ) & ".csv"
Will give you the following filename:
On 24 April 2013
Combine that into a script and you should be able to create all the filenames you will want to import. The filename will change automatically according to the current date.