Link existing D365 FO Sandbox installation to LCS Sandbox environment


I have inherited an orphaned D365 implementation, where the consultant has walked away. As far as I can make out, the implementation never progressed past the sandbox install.

Now the customer (whom i joined recently) would like to restart the project. 

I want to update the sandbox to V10 and start internal training.

Is it possible to link a newly created LCS project to the existing sandbox install; i have access to the previos json file(s)