never thank someone for doing an aveirah on your “Behalf”. THen you are m’chazaking it. Maybe rather, point it out that we are not allowed to daven TO a person and prayers should be directed to Hashem.
Since you opened a discussion here, may I ask a question. And please nobody get offended….is Lubavitch today considered Avodas Zarah? I am asking because there seems to be this trend within it of praying to the Rebbe and looking for answers from him and believing he was/is Moshiach.