This feels like a similar question to the current thread Separate "11 Self" from Life Admin area.
A thought … perhaps from a JDex perspective, just extend the end, e.g. 11.11+Dad.
But those files don’t have to live in your file system, next to your current files. Create a separate folder, populate it only with the IDs you need for your dad’s stuff, and in that JDex entry, just note where it is?