How to improve integrity of Medium choice in MSL Fluid Example ThreeTanks?

Question

I think the MSL ThreeTanks example provides an important example for central parametrisation of components.

The problem with the example is that a person interacting with the GUI can first set the central Medium to a value from a list, and the go on and give the different tanks other Medium, although the default is to refer to the central Medium. It would be better to in the code make sure that the component Medium is chosen to be the central Medium.

I have looked the discussion around the prefix final, but seems not to apply for redeclarations. Also I thought there was a difference between "redeclare package Medium = ..." and "redeclare replaceable package Medium =".

How can the code be improved around the redeclaration statement for the component so they cannot be further redeclared?

The example is Modelica/Fluid/Examples/Tanks/ThreeTanks and the code around a component that I want to improve is

Modelica.Fluid:Vessels.OpenTank tank1(
   redeclare package Medium = Medium,
   crossArea=1,
   ...
   );

I also understand that not all Modelica GUI support access to the central "Medium = " statement in this example.