Autosar How to use application data types which are imported as references?

I need to access application datatypes, which are shared. So I uses the arxml importer with the method update references. Packages are imported as well as datay type mappings, in a read only method.

When I try to define a datatype as Simulink.NumericType it is added to the package Datatype Package and ApplicationDataType Package. But I want to use a datatype which is defined in an read only package.

And when I try to change the base type package to an referenced package (i.e. Autosar_Platform/BaseTypes) (which is also read only) I got an error regarding uniqueness test.

Isn`t there a possibility to use referenced data types, and if so how can I access those?

Kind regards