Thermal considerations on TS83102G0B device in CBGA 152 package

Does the combo lid at the bottom of the CBGA 152 package of the TS83102G0B device participate in the thermal dissipation of the device?

All the thermal dissipation from the die is achieved through the CuW material on top of the CBGA 152 package. 2 scenarios can be considered:
- an external heat sink is used and placed on top of the package: the thermal dissipation is achieved into the external heat sink
- no external heat sink is used: the thermal dissipation is achieved via the Alumina of the package, then via the balls at the bottom of the package and finally via the board

In both cases the soldered combo lid between the balls does not participate in the thermal path. It should NOT be soldered to the application board since this may change the thermomechanical behavior of the CBGA device in the second level reliability in an unexpected and undetermined manner.