All suggestions are welcome.
Our universe is but one of an infinite number, all of which will support some form of life. Each universe has a start and an end and receives its 'matter' from a neighbouring universe through black holes (singular or plural) in the parent universe.
Because the number of universes is infinite in number and their creation and deaths are all staggered, at least one universe will have existed at any given time in the infinite past and will exist in the infinite future. The direction of time is reversed in some universes allowing those universes to give birth to their parent(s). Indeed since time has no meaning in the void which is the 'womb' the universes are born into, any daughter universe can also be the parent of any other universe.
In every one of these universes there exists at least one organism that reaches an intelligence capable of entering, and seeding with their own DNA, at least one neighbour universe. In this way, only natural causes that can be traced infinitely far back are needed to explain the creation of both matter and biological organisms.
How about if you consider there is only one and only one universe. The universe encompasses everything as in elementary set theory.
Or if you insist on multiple universes of discourse, how about using an infinite series of Venn diagrams? The Venn diagrams need not be spherical with boundaries.
This could actually be a systems architecture engineering problem with a subsystems, interfaces and boundaries. With the greatest leverage being at the interfaces which is where the initial intelligent organism enters the system.
Now help me with my profile monitoring using generalized least squares as applied to the human response! LOL!
You better think long and hard about infinitie universes and infinite time because given both ID is a certainty.