Thank you for your post.
The actions you described is by design. The Keychain allows you to automatically login to a database file when it is opened; not via a relogin script. You should instead use a table to store values for a relogin script, and then reference the fields in the relogin script.
If you had a file that does not have an automatic login, the Keychain value will be used to automatically log in to the file instead of being prompted for the name and password.
Then that's just improper design, or somebody's copping out on what is actually a bug. The Keychain is designed to be used for any authentication dialog in the system, and there's no reason that I can think of why it would be limited to an initial login. If there's a good reason, then I'd be very interested in hearing it. I highly doubt that there's any good rationale.
Underscoring my point, the authentication dialog brought up by the ReLogin script step even has the checkbox allowing the user to store the credentials in the Keychain. If this was truly by design, that checkbox wouldn't be there.
Storing passwords in tables is by definition insecure and bad practice, so that's not something that FileMaker should be recommending.
Unless there's a strong rationale why a ReLogin authentication wouldn't respect the system-wide Keychain functionality in OS X, this is a bug that someone doesn't want to admit to.
Once again: this "design" is faulty. It's improper app interaction with the OS.
They Keychain is for any credentials, anywhere. There's no excuse for it being limited to when a database is opened. It's perfectly valid for a Relogin script.
Please revisit this, as the currently behavior is wrong and the design logic is faulty and not well thought out.
The points in my previous post also haven't been addressed: "the authentication dialog brought up by the ReLogin script step even has the checkbox allowing the user to store the credentials in the Keychain. If this was truly by design, that checkbox wouldn't be there."
Someone in development is making bogus excuses for bad app behavior instead of fixing behavior bugs. "That's by design" is the first refuge of a lazy developer. Probably the same bunch as have been ignoring the Dock-bounce nonsense (http://forums.filemaker.com/posts/ebf9e8ba75).
We are suffering from this silly and bad design with hundreds of users on a daily basis. Bumping this to hopefully get an answer; the previous non-answer hasn't addressed why the relogin dialog has a "Store in Keychain" checkbox that is completely ignored by FileMaker: that's not intentional design, that's a bug. Please revisit this and ask the developers to make relogins work with the Keychain just as initial logins do (there is no difference between the two from the credentialing perspective: they should act exactly the same).