Good question Clifford,
I am wondering the same thing. Not every project will have interdependencies with others. I’d prefer to manage these dependencies via coding so noting gets ‘pushed out’ without communication and agreement by the two concerned project managers. I am wondering if it might be enough to look at the early finish of the ‘giving’ project and the late start of the ‘receiving’ project. I’m not even sure with the concurrent projects that are possibly unrelated whether there is any meaning in a portfolio critical path? Finish will be last projects completion date and unless all the projects activities are tied in to each other the same finish milestone that this is even possible.
Happy to hear any thoughts!