There are few things confuse me about what happen to atma after death, even after reading this thread.
There are some slokas which are used in narayan bali puja, I think those slokas are from vedas and garuda purana. In most of the pitru puja, I've seen atma enter into other living body, and that person doesn't know anything about it. My uncle have face such a thing, and me and he both are not fully believer on such a thing. But he said I don't know what happen to him during puja. So is it really possible? Here is another quote from narayan bali puja wikipedia.
"A dummy body mostly made of wheat dough is used. Vedic Mantras are chanted to invoke such lost souls. It is believed that the ritual makes the souls of the dead to possess the dummy body which is later set alight with the pyre supposed to let the soul to liberate and transcend."
I've seen such a thing many time, sometimes it is either fake, sometimes it looks too real. I do believe in vedas, but not in purana(not much).
There are loads of Paliya are in Gujarat. There are many stories which looks true and people really believe on it, even I do believe in it. So those heroes who die there doesn't take reincarnation? Or they attain swarga loka and capable to fulfill their worshiper wish?
Update: You guys talking about yogi, and I"m talking about normal people. I don't see it is duplicate question at all. Here brahamna chant few mantra/slokas and other soul enter into other living body. There are many pitru puja like this, and in all same thing happen. OK I accept that atma can enter into other living body, but for how much time? If atma enter into other body then what about karma cycle? If he/she have done some good/wrong then why don't they take another incarnation? Here many times pitru wait(for example 100 year) for their grandson to do some puja, then it means they can wait. Similarly many bad soul enter into other jiva, I mean how do they have choice to not take another incarnation? And what about paliya? those have died in 15th century and still they did not take any other form? I mean do atma have such a choice?