Web based application and Office-Integration

I developed a simple issue tracking tool with web based application with django.

Users can upload files to a ticket.

Editing office files (MS-Word, MS-Excel) has this workflow:

1. User A uploads foo.xlsx
2. User B downloads foo.xlsx
3. User B edits foo.xlsx
4. User B uploads foo.xlsx again.

The download/edit/upload workflow is too time consuming.

It would be nice if this could be improved.

Server: Linux, Clients: MS-Windows.