Bearing in mind that Uniden primarily is a hardware manufacturer and not a software developer, it isn't very flexible.
That said, you can "fool" Sentinel by creating a second folder for your data, duplicating all files (everything) that is in your primary folder. Then going to the Tools>Options... you can point to the file folder you want to be active. Once you've done that, you can manipulate files as desired. After writing to the friend's scanner (or SD card for the scanner), be sure to switch back to the primary data folder.
This is cumbersome and fraught with things going wrong if you are not carefully paying attention to what you are doing.
I'd suggest going the ProScan route as their main thing is software development and it is more flexible.