What is a "PING" motion?

I have the POA for my parents, my mother passed away only 2 months ago. Last summer, my sister applied for guardianship of my father claiming that I have been "abusing" him and "misappropriating" his money. None of which is true and already disproven. However, on the day of the hearing, her lawyer dropped the motion and told the judge that my father "agreed" to pay all the legal fees, including his, the court evaluator and the court appointed lawyer, (who did not even show up). Now, her lawyer informed my attorney that I have been "siphoning" my father's assets and he will move forward with a "Ping" motion. Once again, none of these accusations are true, nor can he even prove them. I think that he is taking advantage of my sister's mental unbalance to get more billing time. He has made even more unsubstantiated accusations against me, including going so far as to tell my lawyer that I called his office and threatened his staff. I never called his office!! He has made so many outrageous lies about me and my character. My lawyer said to ignore it because it is a ruse to get riled up. However, my lawyer also told me to expect these motions to continue over and over again. What are my legal options to stop this abuse and slander and to prevent more of these frivolous motions? My father is not incapacitated, but this is all very stressful for him because he is still grieving for his beloved wife who he has been married to for 63 years. My mother had a long battle with cancer which was very stressful on him and me. He is only collateral damage to this lawyer. Can I file something with the Bar Association because this dishonest and unethical lawyer violates the canons of the Bar's code?