Scenario:
Requirement is that there must be Document type with each document, so that when document is uploaded from crm to sharepoint the document type can be tracked.
One solution can be to create a field (text field / option set) in CRM & SharePoint and mapped so that when document is uploaded the filed can be filled. But this solution was not found after hours of effort and searching for SharePoint.
One solution can be to create folder as per each Document Type in respective record. This will give option to upload document using CRM in respective site location which will represent respective folder in SharePoint.