We have two, small sump pump pits in our basement, however only one of them has a pump in it. The output pipe is 1.25" rigid, plastic pipe. It comes up out of the pit where I have a joint so I can lift the assembly out of the pit if I have to. Above this joint, the pipe continues to the joists, where it makes a 90 degree turn, goes across the basement, where it makes another 90 degree turn (right above the second pit) and heads out the sidewall.

I want to put a pump in the other pit and tie it into the existing output pipe (if possible).

My concern is whether the existing 1.25 inch pipe could handle the output of 2 sump pumps should they come on at the same time.

Can they?