How to create or find a PVC coupling for a 2" diameter PVC to a 2" 1/8 diameter PVC?
A Fernco type coupling may work.  These are available to fit a lot of different pipe types. They are available at the BB stores or the plumbing supply houses. They provide a lot of flexibility. I would get a very inexpensive caliper and get the exact outer diameters.  Then talk to someone in a plumbing supply house about the right or closest Fernco size. Good Luck. P.