ANSWER:

If they’re actually super Sufis who believe in Prophet salla Allahu alaihi wa sallam being alive and hazir, nazir and they pray to the dead in their graves then one must not pray behind them. 

Kindly refer to the following link(s):

Sheikh please tell me about the muslim group with green scarfs on their heads. Can we follow them in prayer? I heard people say they are sufi sect but I know nothing about them.

Sects | February 18, 2018 1:50 am
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I have a cousin who is following deobandi ppl.And he wants me to join his way too, he is giving me their books and advertising them and taking me to his shuyookh. And he is trying very deceptively, how do I keep ties with him and stay away from the fitna at the same time? I want to save my uncles family (his father’s family) from becoming deobandi too
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Here in India, the Tabligh Jamat is arranging a three days so called “Deeni Ijtema” in Aurangabad city of Maharashtra State. Is the concept of such an ijtema is permissible in Islamic Sharia?