If the BBT is accepted, it says there was a point, which expanded to the current status of the universe. This also says, there was nothing else aside from the first point - else the entire BBT becomes superfluous. Here, we can surmise the possibilities applicable:
1. Space, or its prototype status, was compressed within the first primal point, and spewed out, expansively, in proportion to all other products from within that point.
2. Space was independent of the BB point, and was poured into the universe from another dimension or realm. This factor violates the finite premise.
3. Space is a post-BB product, as are all other universe products, and occured after and outside the BB point.
4. Both the BB point and the universe was the result of an external impacting.
I see no other possibilities, and I favor the 1st one from a scientific pov, and the 4th from a belief pov. The first [1] says there was a program which anticipated and fostered the universe and all its content, alligning with the logical premise whatever came about was resultant on a corresponding program which fostered it. Here, space would be no dfferent from the other products, and can be seen as anticipatory and accomodating, akin to a builder or a program, which would obviously cater to bed or floor to contain a house and its contents.
Thus space is a matrix to rest the universe products - else the products would not/could not exist. The confusion results from space resembling nothingness, but in fact, space is an inert factor, which can cater to all the varied products, without causing confusion. If space was made of terminable material and elements, we would not be able to distinquish the other materials, so we can see why space was made without any material traits, and is a neutral factor. We can see space - it is not nothingness; space can also bend, and it's independent temperature be determined.