I have to forget about my own theory to say, that universe does not need radiation (light) to expand in ΛCDM model, so the infinite number of the overlapping and UNobservable universes would also expand in this model. However, if I don't forget about
my theory, then it's kind of a physical backgroud or even explanation of your "interaction" between all your observable universes, which seem to be physically distinct only by the fact, that CMB passes through all the spacetime points from all directions. Their physicality is still questionable to me.