Take a tough stance with mother. Tell her she needs to start culling photos.
There's no need to keep "RAW + JPEG". Blow the redundant JPEGs away.
There's no need to hoard pics that aren't "keepers" (ie: 40 pics of the same pose, and the one best one was actually sent to the client)
(in my opinion) - there's no need to keep RAWs long term. Edit them, save as JPEG (or fully delete), and blow the bloated RAWs away. (ie: photographers seem to be hoarders; no need to keep some photo shoot of family from 5 years ago that you will never hear from again)
All of this is easily done within the Lightroom interface.
Take a tough stance with mother. Tell her she needs to start culling photos.
All of this is easily done within the Lightroom interface.