You should get your own lawyer so there is no conflict of interest during your case. For example, if you use the same attorney as the driver of the motor vehicle you were riding, you may have to file a claim against that driver.
Your attorney would have to choose who to represent. They cannot ethically represent both the plaintiff and defendant in the same case simultaneously.
There is an exception to this. If you were involved in a crash and your child was also involved, both you and your child might select the same attorney to represent you. This can make gathering information and conducting an investigation easier on everyone.