Unsymmetric Multi Bore Pressure-containing component and how to constrain it?

Hi all!

I was wondering if anyone has a good (accurate) technique for constraining an unsymmetric multi bore pressure-containing component?

I've attachted an illustration of a model:

Suppose each bore can be pressurized independantly (load asymmetry). e.g. in one load case two bores have internal pressure, an other load case four bores have internal pressure and so on

The flat surface introduces geometrical asymmetry

I was thinking of using Inertial Relief, but i do not know the theory enough to know exactly what it does.

Any tips and tricks would be appriciated

(I've attached a step file of my example component)

Regards
Siggi