In a sense, yes, you can build a common manifold that can support 2 or more pump off a single thru-hull. The manifold branches off to each sac's pump, then out from each pump to each sac. So past the common manifold, each sac is completely independent of any others, with its own plumbing and electrical. Layout of the bilge and bilge depth will usually play a factor in if we can do a common manifold or do we need to do all individual thru-hulls or maybe a single and a double.

Pumps do not starve, no issue running 2 or more pumps are a time filling or draining. No issue running one filling and one draining.

So with an existing thru-hull, a common manifold is worth considering, depending on its size and placement.