Hello Marcelo,
I wanted to reiterate what I said here. I had an internal discussion and realized I didn't fully comprehend your post. To reiterate, you have the QuickBooks file on an external hard drive. Two computers with QuickBooks can access the file and make changes. Also, you would be using multi-user mode in QuickBooks. In this scenario, you would choose one computer to be the main computer and install the Method Integration Engine. This computer would be the one who does the main syncing. On the other computer, you can install the Method Listener to allow real time sync to Method.
- Greg