Pondless Waterfall Vault Extension for Use with Large AquaBlox Water Matrix System | 49001, Black

How do you suggest sealing the plumbing pipe hole in the pump vault since there is a 2nd pipe hole in the extension?

What is the total hight of the waterfall vault when the extension is added?

Can two pumps be used in this unit, as I am plumbing for 2 streams. Both streams returning to one vault with 5 large aqua blocks and this pump vault.