Is it permissible to invoke blessings upon the Prophet after the prayer in the mosque with the Imam?

Prayers upon the Prophet, peace and blessings be upon him, are always prescribed. However, one must beware of innovative prayers, such as "Salat al-Fatih" practiced by the Tijaniyya, which has no basis in Islamic law. Some of them even claim to have received it directly from the Prophet while awake.