Hello Al
When doing a debt management plan, you should definitely focus on the debts that are in your name alone and showing on your credit file. Get these sorted first as these are the ones which are going to effect your ability to get credit in the future.
If you think you have other debts such as the shared utilities, the key is whether they are actually taken out in your name or not. If your name was not actually on the bills, then those creditors will not chase you and in fact will probably refuse to deal directly with you.
Have a word with your debt company about the changes you want to make and they should do the work for you. After all I guess they are taking a monthly management fee from your payment.