Hello,
The problem is that the device ID is created on the client side when the app initially loads. That record is stored in the browser's IndexedDB local storage as the _first_ row. So, out of the box, you're not going to know what that device ID is going to be on the server side (at first).
However, that device ID IS stored server side in your single settings table and you could use that device ID in a filter.
So, this is what I do....
I have two tables involved in my disconnected web app's authentication, the single settings table and my user's table. When the user first loads the disconnected app and enters their credentials, a POST to the sync server is made with their Username and Password sent as parameters to the WebHandler's p_web.Authenticate method. I validate the passed Username and Password against my User's table.
Now, here is where you could grab that device ID. If the passed Username and Password validate, store the deviceID in that User's record. Now you know that device ID goes with that user. Side bar on that though is that the user can have multiple, dare, numerous devices so you may need a child table (User>->>Devices) to store that user's devices. Once you have that sorted out you can control who get's what in the Sync Methods.
I don't know if you have a NetTalk Progressive Web App currently up and running but it is INCREDIBLY cool! Most people outside of the tech world have never heard of it. Yesterday afternoon, I used mBuild to create an iPhone app, an Android app, and a PWA in just a few minutes. Brought my Sergeant in and he happened to have an iPhone and Android phone with him. With my phone and his two phones, I demonstrated the iOS app, Droid app, and PWA side by side and you couldn't tell the difference. It's just freaking cool! What Bruce has done with the disconnected app stuff is a great credit to him and Capesoft.
I'll be doing a walkthrough of a NetTalk created disconnected app during the ClarionLive weekly webinar on Friday, December 21st. Bruce should be there as well. This would be a great opportunity to ask questions.
See ya,
Don