@SimonKay It’s impossible to troubleshoot your issue without seeing your code. Were you having success with it working as 2 steps before you turned it into 5 steps? I would start there before you added to the complexity of the form. Begin with two forms, use @thesnappingdog example, and see if that works. Find out if it is handing off the email to the next form with just 2. If it doesn’t, post that code, and any errors in your console when it doesn’t work. If it does work, try 3, and so on.
My example and his example traverse down a Javascript array differently, so which one are you using? Did you try the other? Try outputting the email variable to your console log -- see what it says. Is it blank? Does it output the email correctly? When you go to the 2nd step, inspect your email field… did it place the email value in there for you? You need to check all of these things to make sure you are actually passing the email variable.
Good luck.