What year, make and model coach do you have. Are all four batteries that you describe in our posting for the "RV" part of your unit with two more for the chassis for a total of six, like most have, or do you only have two for the chassis and two for the coach? If you actually have six, which would be two for the chassis and four for the coach like shown in Bill's posting above, you definitely should have all four batteries be the same make, size, type and vintage. Battery banks are not a good place to mix and match.
It would be really good for you to add the make, year and model of your motorhome to your "signature" on this website a so that information will always be there on your posts. It will hugely weed out those that can help and those that maybe won't have good knowledge for your particular application.
Jim & Angie, Boise, ID
2006 Monaco Dynasty Countess III
2017 GMC Acadia Denali