This program uses the MIA lists on the Redump Wiki to add "MIA" tags to the corresponding discs in any inputted DAT files.
You can either simply open the program and manually input a specific .dat file, or a folder containing .dats, or you can drag & drop any combination of files and folders and the program will recursively search through all of them to find and check any .dats within.
It won't automatically replace the original inputted DATs with the new, updated ones, but you can select at the end if you would like it to do so.
So far I've only tested this program on Windows 10 and with Python 3.11.0, so I can't make any guarantees for other set-ups, but let me know if you encounter any issues and I'll try to fix it.
[Note: Requires external modules, "BeautifulSoup" and "lxml" to run properly.]