Basement Ejector Basin Vent

[TMetz60]

Our contractor "roughed in" the plumbing for a full basement bath. The ejector basin/pump sits just outside the wall behind where the toilet and sink will be. The shower drain (currently under a drain box in the concrete) the toilet drain and the sink drain all run under the concrete and into the basin.
There are no vent stacks anywhere in the vacinity. However, I noticed that the plumber drilled 2 - 2-1/2" holes through a 10" wood support beam and left a couple of short 2" PVC pipes through the beam, probably as a clue to the future owners (us) what they were for.
In the same joist run about 18' away are 2 pipes stubbed out of the main 4" drain for the house. They both point towards the 2 holes in the beam.
1 stub is 1-1/2" and sits about 4-5" higher than the other 2" stub.
I know the ejector basin will have the 2" pipe that threads into the base of the sewage pump and that the basin lid has to be vented.
So here I finally get to my question: Is one of the stubs off the main drain line designed to have the vent from the basin tied into it???

Thanks in advance.

[AllanJ]

The basin vent should connect directly to a vent stack, not to the main drain that in turn connects to a vent stack someplace else.

Also there should be a pipe to a vent stack where the toilet discharge meets the drain line.