Taking Black Hole Cosmology, Zero-Energy Universe and Many-Worlds into consideration.
Imagine this kind of Multiverse system, each, and every single Singularity within a black hole creates a new "Primary Uni-Reality" via the Big Bang from which from that very moment to every other eventuality in the history of that universe, "Infinitely Branching Parallel Uni-Realities" manifest into existence via infinite probabilities of that same event splitting off into different cause and effect chain of events leading to different histories, effectively creating the multiverse.
Since black holes are most likely universes all the way down, the only reason that conservation of energy doesn’t thin out the creation of lower universes due to mass loss is because the amount of positive energy (same amount of mass) & negative energy (same amount of gravity) in all of the universes equals zero. Same thing with temporal probability divergence.
Now, take into consideration how many black holes there are.
If there are about 40 quadrillion black holes in our universe, let’s assume that a Higher-Universe (Ω+1 Meta Uni-Reality or The Megaverse) had slightly more or slightly less that quantity of black holes.
If that were the case, the amount of "Primary Uni-Realities" within the Megaverse would be always somewhere around 40 quintillion (give or take). If the timeline splits into separate realities on the new universes, it would be an infinite number of universes, but a finite yet large number of multiverses within the megaverse (around tens of quintillions).
What do you think of this system of the Multiverse? How many neighboring multiverses could you imagine there being?