There is a process of pitru shrAddha as per the tantra. But it is a restricted process hence not known open to general public but only the initiates or dikshitas.
kaulashrAddha is the annual ceremony performed for dIkShita pitR by the son who necessarily is also a dIkShita. Nevertheless, kaulashrAddha can be done by any dIkShita for any other diseased dIkShita. But performing the antyeShTi and maNDalamelana is a pre-requisite for performing the kaulashrAddha annually.
Unlike in the vaidika shrAddha, where the pitR-s ascend to the position of "vasu", "rudra" & "Aditya", in kaula, the dIkShita is raised to the state of "mitresha", "ShaShTIsha" & "uDDIsha" whose position is in the ultimate triangle of the shrIcakra.
gurupUjA or gurupAdukApUjA etc form part of one's nityAhnika as part of upAsanA.
reference is available in trikUTArahasya which is adapted in PKS (parashurAma kalpa sutra) in the sAdhAraNakrama
It is also possible that the guru doesnt have children... but his shiShya-s are eligible and entitled to perform his antyeShTi/maNDalamelana and thereafter the annual shrAddha ceremony. The only qualification for the disciples is that they are pUrNAbhiShikta-s. If a dIkShita has neither children nor shiShyas, his antyeShTi/maNDalamelana can still be performed by any other qualified dIkShita.
Similarly, in the case of the son being a dIkShita and the father being adIkShita, the son can and should still perform the antyeShTi/maNDalamelana by the mantraprabhAva of panchadashi after which the diseased pitR are assigned the dIkShAnAma from the mAnavaugha for eg.. gaganAnandanAtha / gaganAmbA.
Also, a dIkshita can also perform it for a deceased non dikshita who is not a relative, if he wishes.
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