I'm trying to number a document 1, 1b, 2, 2b, 3, 3b, etc.
How can I adjust the page numbering so that this will automate and I wont have to manually adjust the numbering for every other page?
You don't. ID can number 1, 1b, 3, 3b... through some previous page number marker trickery, but unless you restart numbering using the section and numbering options on each spread there's no way to get the intervening numbers and still have independent pages. You might get away with creating a full spread on one double-width page, then place that into a true facing pages document for imposition and printing, but I wouldn't guarantee that will work.
Another option is to make a number list and place it as a text file once your document is finished.
I knew you couldnt do that with just ID, but wasnt sure if someone figured out some code to work around it.