I'm looking for an app (preferably windows desktop, so that it could create a directory for seamless file transfer, but web would be acceptable) that will let me take my numerous cloud storage accounts (preferably at least DropBox, Google Drive and One Drive) and convert them into a single drive.

Unlike http://softwarerecs.stackexchange.com/questions/14077/cloud-storage-consolidation-application, I'd like this drive to share file space between the accounts. E.g. one file might end up in Google Drive, another in DropBox.

Say I have 7GB of DropBox, 5GB of Google Drive and 10GB of One Drive. This combined drive would ideally offer ~22GB of cloud space.

Optionally, the ability to designate files or folders to be mirrored across the cloud accounts would also be useful, but is not essential.

I would be willing to spend £30 for a one-off payment.

Does this exist?