Yes, you can use one of your accounts Business Class Portal Website (BCPW). You must first register your BCPW businessclass.comcast.net click on 'register your account' button/link on the right, then use any email@example.com to setup your administrator email address. However, there is no means by which Comcast will set you up with a single billing statement for all of your accounts. You may want to consider contacting 800-391-3000, use the billing option, then ask the billing agent to send you over to a Premier Account Representtative. A Comcast Premier Account customer has a minimum of 15 accounts , which you indicated in your post you had 16. This may get you to exactly where and what you are looking for.
After you are logged in you can click on the middle SUPPORT button/link and type into the search text box Link Accounts, then click search and it will provide you all the information you need to set up your other accounts. Here is an example from this area. Setting up all of your into one of your account BCPW will allow you to access, pay manually, setup auto-pay for all of your accounts.