Business Setup

We operate 2 businesses that we are looking to consolidate into one main business.  Each business has their own EIN but again would like to consolidate to simplify things.

Essentially we would like to have MAIN business with EIN # and then set up the secondary (similiar business but seasonal) as MAIN business with DBA.  I would like to have 2 seperate bank accounts to track income and expenses.  Is there any reason why we couldnt do this for tax purposes? 

I currently have 2 company accounts set up in QB but I do not really use one of them.  Now that we are getting busier I would need to maintain both accts.  Some of our customers use both services so I feel like it would make things easier to have my current customer and vendor list combined for both companies.