Is it correct to say, and typical, that parallel lifetimes are parallel in a partial sense, that they may have different beginning and ending timepoints, relative to the current life? Or do they all have the same starting point at least?

This is difficult to envision because you are so enmeshed in the illusion of linear time that it is hard to imagine parallel without a linear aspect in relation to the current timeline you see unfolding during the course of your personal experience as a living physical human. The best way we can describe this for you is that time is a circle and so the parallelism is imbued in the return to the same point on the circle when traversing what it encompasses. So rather than a series of lines going off towards infinity that are on a separate track each, and not crossing one another, and therefore independent and only relatable with respect to that linear projection from the past to present, and then off towards the future still unfolding, everything points back to the current moment regardless of where it is on the circle, so the parallel lives are essentially taking place in this grand looping. It is more complex and intricate than a single circle fitting all the lifetimes into discrete segments along its path. Parallel does also mean "a simultaneous character or aspect" but in the broadest sense it means "independent" so it is not necessarily governing the current moment or dependent in some way on the timeline per se to describe where it is occurring and when, with reference to a linear life being lived by a physical human pondering the question. So the various lifetimes are present within this circular loop and, in a sense, are sharing the continuity of the soul in a deep sense, but experiencing discrete events by a portion of the soul as witnessed, and these discrete experiences cannot be referenced with regard to linearity in a very precise way because of the very looping we speak of. There can be contiguous portions in a sense of past, present, and future in close proximity and their future extensions as well may be contiguous, not overlapping in the sense of physical presence being simultaneous, but contiguous meaning "closer by than further away." This is the best we can relate to you these interrelationships, but because of the circular nature of the looping, no individual lifetime of a given soul is very far removed from the present moment. This also relates to what you were shown recently, that the life being lived in the moment can be relived through this looping and without making a change in status from the standpoint of the observer. This is an enigma that relates to another question you will be asking here, but it is important to understand the implications, that in a sense the parallelism of the lifetimes under discussion here are themselves a kind of reworking of the personal experience of the soul extension you believe to be yourself. In a sense, it is in the looping creating a new timeline as the loop comes back around to where you are in the current moment, and a new lifetime can literally begin and head in a new direction. So this is a very complex undertaking because there are many inspirations for the lifetimes lived and many purposes. It is a decision made by the higher self and the soul itself to spawn a new portion of itself into a new action of some kind. Much of this is being done to explore the universe and its many opportunities for learning and growth through understanding the shades of meaning in various kinds of existences. When a life is desired to be lived within a particular paradigm, that is when this is formalized into the so-called lifetime that is done in parallel through making the decision to launch that life with a beginning and an expectation of a middle and an end at some point according to the operating principles of the paradigm in question. This can come at any point relative to the current moment of existence experienced by your physical human self. It could have happened already many, many times prior to your reaching this moment of your current life and may add additional starting points as you proceed from here. So with the looping of time these will be catching up to the current self and will, in effect, have a kind of spiraling where there is a return again and again to make every portion of those lifetimes closer in becoming more contiguous to your current point in life.