Simulink Test AggregatedTest Coverage Results

I have a model which uses two systems. I have created three test harness, one for each the systems (Test_Harness_A and Test_Harness_B) , and one for the general model (Test_Harness_C) which tests the integration between the two systems.

I have a good coverage on test A and B however I am not able to make the Test Manager, which has all three test harnessess to compute the Aggregated Decision coverage when running Test_Harness_C. The result of the Aggregated Coverage Results is 3 analyzed model with independent coverage.

Is there a way to correctly compute the agregated coverage results?

Note: If I have multiple harness from the same module I am able to compute the aggregated coverage.