My immediate Blithe Spirit thoughts were:
Either, we go with the Tregorran / Carol / JD triangle. Compare and contrast - this time it's the bloke who is the dead one and the women live.
Or, Edith is the conduit for the spirits so Soosan is the conduit for the spirit of Emmur and the ensuing triangle with the Grundy boys. In the play the only solution is for Mr Lynchpin to run away, leaving the two wive behind. So Emmur will be leaving Ambridge too?
I think this literary angle to TA is a bit of a mistake. It makes you realise that there are only Seven Basic Plots in the world and TA have probably run them already, several times. Instead of making them look academic, it makes them look as if they have run out of ideas and are resorting to nicking other writers' tales. They would do much better to read a few RL Borchester Echo (not least the Court reporting) and get some believable, current storylines from there.