You do not need many different witnesses to testify about the same facts. Bring the witness with the most reliable first-hand knowledge.
First-hand knowledge means that the witness saw something that helps prove your case or is an expert you have consulted about a particular subject.
Example of first-hand knowledge:
"I saw the whole incident and here's what happened..."
I was there when Joe was cleaning the apartment and he left it in good condition."
The judge or hearing's officer will NOT be interested in the testimony of a person who is repeating secondhand or generalized information. Character witnesses do not help. They may say you are honest, but they usually do not know the facts of the case.
Examples of secondhand information. DO NOT USE THESE WITNESSES.
"I know Joe is a good, safe driver and would never have done anything reckless."
"I heard from Sarah that Joe left the apartment in good condition and I believe her."
It may help your case if you talk with your witnesses before going to the hearing. You can not force or coach your witness to give false testimony! However, witnesses often unknowingly may give the wrong impression, or stray away from the facts of the case. Talk to your witness/es to see what they would say if they went to court for you.
After discussing your witnesses' knowledge of the event, you may decide if you do not want that person to testify. It is better to decide before the hearing. DON'T WAIT until the witness is in the middle of the testimony when you realize that the testimony will not help you.