It will not be a problem for you to sync OneDrive with OneDrive for Business anymore. Because with a free web app -- MultCloud, once you sign in, it only requires accounts adding then you can easily do sync between OneDrive and OneDrive for Business in 3 methods: directly drag/copy options from contextmenu/transfer service under “Transfer” tab. Many other features are available in contextmenu such as preview, share, etc that will help you a lot as well.
Well, as you see, MultCloud supports more than 20 cloud services, so you can also move or backup files between other clouds such as transfer files from Dropbox to OneDrive for Business.
*Update: MultCloud added a special Cloud Sync service now, you can use it to do sync cloud drive task directly. MultCloud provides 8 normal sync ways. And MultCloud supports OneDrive for Business and Dropbox for Business.