myldsmail Google Drive is full

My son is serving a mission and his Google Drive account is full or at "quota" (30GB). I've transferred his photos/videos over to a family Google Drive Shared Folder with more space so he can continue to upload photos, however since he is still the owner of the files they still count toward his quota. He has tried transferring ownership of the files that he moved to the shared family folder, but because he is in a different "domain" (myldsmail I assume) it wont allow him to transfer the ownership.

Guessing others may be having the same issue, so wanted to see if there are any suggested solutions. At some point when he returns home from his mission and needs to transfer all his photos to a personal account he will need to figure this out.

Thanks in advance for any guidance.

The only way to transfer ownership in this situation is for you to copy all of the photos to somewhere outside of Google Drive, then add them to Google Drive again using your own account.