My question involves a child custody case from the State of: CA

In two weeks, my parent will appear in the court to answer questions from judge to be non-professional supervisor to my son. I have a mis-demeanor domestic violence to my ex two years ago and now in supervised visitation for one and half year. I have no violence to my son.

The problem is in my former psychiatrist report showed my parent had physical violence to each other before(without any crime committed). So my ex proposed that she worried that my parent will think violence to child is normal. I think the judge will ask questions to my parent about this. But I donot know how it would be. What kind of questions shall I prepare for my parent?

What I can think of to explain this is:
1. My parent pushed each other 30 years ago. After they are 40 years old, they have no physical violence.
Or I can say there is no violence before and my parent testify that they had no violence before.
2. Since my parent has no crime record before, what my ex proposed is irrelevant.

Please advise.

Many thanks.