Hi there could you help me with the ABA rule and one subsection that I could apply in this case

Suzy Shingle is a solo practitioner and is one of only three lawyers in a small town. Suzy is presently defending a client in a criminal action for assault and battery. This morning one of Suzy's regular clients, a gas and grocery store, asked her to sue the same client to recover a past due amount on a gasoline and grocery charge account.

Would it be proper for Suzy Shingle to represent the gas and grocery store in the charge account case?