this is what I have done, to get it working. I have tried to lay it out as best I can.
on completion of document management settings a library called "Account" based on the entity Account was created in sharepoint.
I noticed that when you create a new document in CRM it creates a new folder in this library on SharePoint, based on the account name (if accepting the defaults).
on the local server I have a folder c:\data (Domain share)
reconfigured onedrive to sync with a new library and set it to sync with sharepoint library "Account" . set the save location to point to c:\data
A new sharepoint Link (folder) is created in the data folder, c:\data\sharepoint-account\
I have a parent folder called "companies" which contain about 60 subfolders each named according to my clients these folders then contain plenty subfolders. I moved all folders out of "Companies" and placed then in this new directory "sharepoint-account" displaying one folder for each client (Account)
ie
c:\data\sharepoint-account\client1
c:\data\sharepoint-account\client2
c:\data\sharepoint-account\client3
In CRM I open an account and then open the document form.
select "Add Location"
replace the default folder name to match the folder name on the server ie "client1" (without quotes) you will be prompted to create the folder followed with an error that the folder exists, with the option to associate the record id
once submitted all document including those in subfolders will populate the document form.
now the users can create new document on their pc save them to the shared drive \\localserver\data\sharepoint-account\client1
onedrive will sync to SharePoint and CRM will reflect the new doc under the client1 account.
Hope this helps any one out there with this issue