Salat Behind Shia Or Ahmadia Imam
One should be clear in mind that a Muslim can pray behind a Muslim prayer leader, whatever his faith i.e., shia sunni deobandi barelvi or any other but not behind a non-Muslim. Since qadiani are non Muslim, one can’t pray behind a qadiani imam. Otherwise his iman will be lost. Also one is not allowed to pray for a non Muslim. So one can attend janaza of anyone, Muslim or non Muslim but can’t pray namazejanaza for non Muslim. This is the basic rule. Rest one can decide himself as no one is responsible for other’s deeds.