Thanks Josh, yeah, that makes more sense, I was wondering, how you would be able to update not-one-to-one mappings... it would be difficult if not impossible...

So I am now using the built-in query/table as the source for the store, and still I have to do the trick above with setting .phantom to false, so that not 'insert' is fired, but 'update', but now I get an error:

Could not save changes due to the following error:
Value for key field 'gsid' was null or not supplied!

where 'gsid' is the required primary key (along with the container).

I am not sure, where/how am I supposed to supply it...