You cannot access the File Options I don't think. But you don't need to. I very seldom need to type to log in to local files on my machine. I drop them on an AppleScript droplet (Save As "application bundle", don't check any of the options).
on open (theFiles)
tellapplication "FileMaker Pro Advanced"
opentheFileswith passwords "your pw" for Accounts "your account"
You can also create a Filemaker "Opener" file that does this without applescript.
Give this file the same account name and password as your main file.
Set file options on this file to open with this same name and password.
Write a one line script: Open [Yourmainfile]
Use file options to specify this script to run when the file opens.
You can even create several such files, each set to open your main file with a different account and password.