Hi Rasvanya,
The shareable application models are not intended to be a parent/child relationship. It should actually perform as you described so that there is only a single version of the application model. If you read the help file in Blue Prism regarding this topic, it describes situations where you'd want to only have a single instance of a business object/application model.
What's the reason that you're looking to have this functionality? Are you looking to split up the business objects for an application so that the parent has some kind of top level set of elements and then each child object would have the elements of some subpages of the application? Is this a huge app or can you just allow all the elements to be in all of the objects that share the application model?
Respectfully,
Dave
Dave Morris, 3Ci at Southern Company