Calling a notebook from a different notebook

Basically I have a notebook (let's call it nb1) that when evaluated yields one number when I specify some parameter $\alpha$ (in nb1). I want to call nb1 in a different notebook (nb2) using for instance the NotebookEvaluate function, such that I can use the value calculated in nb1 in my second notebook nb2. Is there a neat way to do this, that also allows me to evaluate nb1 for different values of $\alpha$?

For concreteness I would like to do something like this in nb2:

tab = Table[NotebookEvaluate[nb1],{alpha,1,1000}];

My question is: What do I have to write in nb1 to run the table command as above?

I hope the above pseudocode illustrates what I want to do clearly.

I do not want to convert nb1 to a function, because the notebook is so long that I'm bound to run into a bunch of unforseen errors.