You can enter them in the same account. When you buy one transfer the cost to the Savings Bond account. If you set it up as an investment account then enter a buy with the cash.
How are you going to enter the accrued interest? I update my interest only once or twice a year.
I use the Treasury Dept savings bond page. They used to have a Saving Bond Wizard program I loved but they discontinued it. Now they have this, Calculate Saving Bonds
Individual - Savings Bond Calculator for Paper Bonds