My wife is old school. She doesn't want our photos in the cloud. She wants it on her computer.This isn’t helpful either.
If you’ve filled up 2TB the problem is the workflow!!! That’s an extraordinary amount of data. I would suggest that most of it represents and incredible amount of wasted space.
Given that this is not a point of flexibility for their needs then the answer is money. Spend the money on a solution that works. Start saving up though cause that workflow will require an 8TB solution if five years time.
Could I put all of her photos on the NAS? Sure. Does she want that? No.
If her data grows to 8TB in 5 years, that's not that big of a deal. 8TB Nvme drives will be available by then anyway.