It seems to overly complicate things. Just let me create or reference stack in one go within the API.

let baseNetwork = new pulumi.Stack("pr-123", {
  config: {
    someStuff: "test", 
   },
   secrets: {
     somePassword: process.env["password"]
    }
});

if it doesn’t exist, it creates it. Every resource created after that is part of that stack.

I actually dislike the current design, my suggestion is an overhaul.