ewallet share & sync between two users?

I'm trying to help a couple that's been using eWallet by Ilium Software, but has recently stopped syncing between their devices.

Here's the scenario,

He has iPhone & iPad, both fairly new

She has Mac Book Pro, iPhone & iPad, also both fairly new.

They were set up to sync to the eWallet file that was in his Dropbox account & this recently stopped working.

I was under the impression that syncing via i Cloud would be the best option, but the best I can get is all of his devices will sync between each other & hers will sync between each other, but there is no communication between his & hers devices. I had assumed they had the icloud set up with family sharing option, but eWallet's support says its an Apple limitation that makes this not possible & I would need to go back to the Dropbox method, which stopped working!

Is anyone using this app in this type of scenario with any success & if so, can you give me any advice?

Thanks!