Is there an Afterlife?
From a broad perspective, including the scientific, there is little evidence for an "afterlife." Most claims come from a variety of places ranging from wishful thinking and religious teachings, to fantasy and various psychic experiences. We cannot easily believe religious leaders and teachings for those gain their "evidence" from mostly faulty writings and consequent "teachings."
The best evidence for afterlife is actually from teachers, who are NOT religious, but who have themselves gained access to a higher consciousness and its "peak experience". Such teachers do not promote anything or require anyone to believe or follow them. Rather, such teachers share their own experience of the afterlife, or an enlightenment experience, and leave it up to students to find the experience themselves, most often by following a non-religious, non-denominational code of self-study, self-improvement, and self-actualization. Various religions actually have such teachings, that are mostly ignored, that include virtue development, meditation, and working for the good of mankind. Kabbalah, Zen Buddhism, Christian mysticism, Kashmir Shaivism, are some of the Ways that lead to one's own experience of enlightenment and abiding Life.
For more, you could see the documentary production that a filming company made about my own such teachings on Vimeo.com under "A Path To Abiding Joy."
Although there is no "proof" of a supreme being, or of life after death, the fact that we are HERE is mighty compelling, and makes the case for mystics (those who believe that an experience of the infinite divine can be had here, on planet earth, while still in the body, by following a genuine, selfless path to Self-realization).
It is possible that as the soul migrates, as it were, through life-time(s) that so called alien existences or relationships or even identities take place as part of the journey. That would remain to be experienced through the methods I have suggested above.
As for myself, I have followed the path to this light, and have had my own convincing experiences resulting mostly from genuine virtue-developed meditation, and there is no doubt (for me!) that even as the universe deteriorates (entropy) there is an enlightened state that can be achieved and accessed where all things make sense and where all things work together unto good (syntropy).
If you wish to study this further, I recommend Autobiography of a Yogi by Swami Yogananada. Your questions to be after reading the whole book would be much more incisive.