So for a Kylchap you would have follow the above procedure for each stage, estimating values of M (entrainment ratio) for each stage taking into account that the propelling fluid is the mixture from the previous stage, and that the pressure ratio will be affected by the back pressure from the upstream stages.
Yes. Quite a challenge! But I was only trying to illustrate another way of thinking about the problem.
Maybe better to accept experimental findings that such petticoats will not beat a well designed Le-Maitre or Porta setup.