Backup multiple PC's to same repository, security



I’ve read some related posts, but don’t think this has been asked as such. For my family members, I’d like to have them all backup using duplicacy GUI (licences bought), and all backup to a single Google Drive account where I have unlimited storage. I’d like to prevent the case though, where one user’s poor Windows / Mac password choice exposes everyone’s data (i.e., my understanding is that the Windows / Mac main password encrypts the storage encryption key).

So my thought is to use one Google Drive storage directory and different encryption keys. Is there any advantage to that vs. just creating a different Google Drive storage directory and using a different encryption key?

I’m also, of course, open to other ideas on why I should or shouldn’t create separate directories and/or use separate encryption keys. I know I’ll be giving up duplicate-free backup by using separate encryption keys (i.e., same file in repository will look like two files in the storage, so will be stored twice).