Welcome back to the Wefugees Community and thank you for reaching out to us again.
I am sorry to hear that you find yourself in such a difficult situation. Unfortunately, the official procedures here in Germany can be quite complicated. As I tried to explain in your recently opened thread, before you are moving to another city (or rent a house), you need to apply for the so-called "Umverteilungsantrag" at the immigration office of your "destination". I am afraid that only because Essen and Dortmund are not far from each other and your family is now in Essen, the immigration office in Dortmund will not confirm your application. But that is only an assumption. If you would plan to move in with your family, it would be a different situation. Are you sure the lawyer recommended you to sign a rental contract without you having the permission to move to another city? I would be a bit surprised if he/she did so. Maybe you can clarify this.
If you would find work in Dortmund, this could really support your "Umverteilungsantrag" though.
I will also link two of our experts here. Dear @mbeon-Ruth or @mbeon-Rukundo, can you give some further advice here?
In any case, please don't hesitate to get back to us with any further questions.
All the best,