Can I add a mailbox to address for casita? How to split utilities?

[Jessica Lamont]

Hello! I’m purchasing an investment property that has a main and an attached casita with private entry. I want to rent them out separately and wondering if I’m able to just add a mailbox and label each door as ‘A’ and ‘B’ 

Also, how do you separate electricity/utility bills for each tenant? Do you just include all utilities in monthly rent since it’s coming from one breaker and water account? This is in Arizona. Thanks! 

Thanks!