I don't see how she could avoid testifying. If one side doesn't call her the other will. She's too central to the case to not be called.
Anyone who doesn't want to hear legal rambling should probably skip my posts.
Well actually over here it's more complicated than that under the law, believe it or not! I actually just researched this issue last month. (We have every intention of introducing the defendant's prior ourselves but we wanted to have the first word on it to the jury.)
So to bring in a prior conviction of a defendant to impeach them if they testify. The current rules in my state require that there needs to be an element of untruthfulness, dishonest act or false statement otherwise it shall be excluded.
The phrase "dishonest act" only applies to a narrow subset of criminal convictions, thus the crime must include the elements of a dishonest act or false statement for the prior conviction to be admissible.
According to the Supreme Court "theft" does NOT meet the criteria of a dishonest act or false statement unless a fraudulent act or deception is involved (i.e. theft by deception or identify fraud.)
I was rather surprised myself at this finding. However it made sense once I thought about it. You can be charged with theft without being dishonest. There are misunderstandings, forgetting to return a rental, etc but fraud or deception means the intent was there.
These little nuances in the law complicate things a lot!