Using external increment value for renaming?

A newby here - I'm trying to rename files and folders in which the new name includes an incremented value based on an external source, i.e. from a folder/file name or content that is outside of the name of the folder or file Hazel is currently looking at. I can create a rule to fetch and increment the value within Hazle, and another to rename the folder/file, but haven't figured out how to get the incremented value to the rule that is renaming the folder/file.

Can Hazel fetch (match) a value from a file, and then apply that value in renaming a different file within the same rule?

I know there is a counter variable, but apparently only 1 per folder. I need to use different increment values for various files finding their way into the folder one being watched by Hazel.

If I can't do that within Hazel, can I call out to a script which returns the value which Hazel can use?

Thanks!

You'd have to use a script for that. Either a shell script or AppleScript can be used via the corresponding actions.