Indexing Sheet Reference Numbers Using Data Fields

Hello,

I am wondering if there's a way to automatically update the Sheet Numbers referenced in this area (highlighted below) based on file name.

I have looked at using a Data Field linked to File properties, but I can't seem to find a way to only use the Right 2 digits of the file name.

I imagine there must be a way to incorporate a Macro or a similar function to the Excel command "Right (2)" to where it would pull the right 2 digits from the file name and link it to the field in question. This would greatly speed up this aspect of plans production as right now my method to complete this is the following:

1. Open Sheet Navigator
2. Start multi-edit and select all sheets in a sub-component (roadway plans for example)
3. Edit Sheet Title to "Roadway Plans ()"
4. Go sheet by sheet and change the number

This isn't too bad for smaller projects, but upwards of 20 plan sheets it becomes a cumbersome task with having to change Roadway Plans, Utility Adjustments, Traffic Control, Cross Sections, etc.

Anyone have a suggestion on how to get the Right 2 of a file name linked to a data field? Or is there a better workaround/workflow that would alleviate this? 

Thanks!