I am planning of connecting a 1.5" PVC shower drain line (a new shower i am adding to my bathroom) to an existing 2" PVC line that goes from vanities to main PVC down drain.

The problem is that if I cut the existing 2" PVC drain line between the vanities and the down drain so that I can fit a connector, I cannot move either side of the existing PVC line (this drain runs horizontally between the wall with vanities and the opposite wall with a the main PVC down drain. And if I cut the horizontal PVC line to just slip in the connector, then I cannot glue the connector.

What is the correct way of doing this?

Help deeply appreciated!

I am planning of connecting a 1.5" PVC shower drain line (a new shower i am adding to my bathroom) to an existing 2" PVC line that goes from vanities to main PVC down drain.

The problem is that if I cut the existing 2" PVC drain line between the vanities and the down drain so that I can fit a connector, I cannot move either side of the existing PVC line (this drain runs horizontally between the wall with vanities and the opposite wall with a the main PVC down drain. And if I cut the horizontal PVC line to just slip in the connector, then I cannot glue the connector.

What is the correct way of doing this?
Help deeply appreciated!!

First off I would use a 2 X 1 1/2 " street wye to cone off the vanity drain, Measure from the base of the hub to the street end of the wye. That will be your cut. Now take a 2" shielded coupling and slip both the robber sleeve and the metal coupling back over the 2" drain. You may now prime and glue the hub of the wye being sure to give the branch of the wye some slope. Now slide the rubber back and tighten the coupling. You may now connect your new shower. Good luck, Tom