Why is it important to have an overview of all your existing debts?
An installment plan only works if it is based on reality. If you don't know exactly how much debt there is, you run the risk of making a plan that falters from the start.
That is why a complete overview is not a formality, but the prerequisite for a solution that lasts. Compare it to a doctor: he can also only prescribe the right treatment if he knows the whole picture.
So always share your other debts with the bailiff as well. They help determine how much you can pay each month and whether a proposal is feasible and acceptable. Without that overall picture, an arrangement can crash along the way.
Tip: be honest and complete. This is the only way to create a plan that does what it needs to do: reduce your debts at a pace that can be maintained, while at the same time working step by step to create financial breathing space.