Here's my answer which is based on what I've learned from my readings: most of us wait on average 70 - 100 years to reincarnate so all our loved ones and/or family members can join us on the other side. Then we can evaluate how well we handled teaching each other and learning from one another our designated life lessons. If there's any karma that needs to be balanced with each other, then we can incarnate together again.
I'll give you an example to explain this. Let's say we have two souls named Adam and Eve. Adam in lifetime 1 marries Eve, cheats on her and leaves her pregnant with his child. In lifetime 2, Adam needs to balance out this karma. So maybe he marries Eve again or decides to take care of her as a parent in the next life. Possibly, he needs to experience a similar pain to understand and empathize with Eve's plight so she leaves him in lifetime 2. But let's not forget the child he abandoned in lifetime 2. Adam needs to balance the karma here too. So he might choose to significantly help this soul in lifetime 2 as either a great parent, helpful teacher or mentoring boss. But Adam is still Adam, so maybe in lifetime 2, after Eve leaves him, he begs and gets her back. Eve, being the nice person she is, agrees and then he cheats on her! So . . . in lifetime number 3 he's got A LOT of karma to balance with Eve. Do you get the idea? He can't work out this karma with Jane Doe. It needs to be worked out with Eve, so even if he dies in that lifetime at age 20 and Eve lives to 85, he needs to wait for her to come over to heaven. Then after her life review, he'll need to sit down with her, their guides and higher counsel members to plan out the best scenario in lifetime 3 to address these issues.
I always tell people that if you meet someone and feel this inexplicable lust and desire for them, watch out! It usually means your soul implanted that desire in your path so you couldn't refuse the person you need to work out a past life issue with.
Miscarried or aborted souls often will return quite soon. Miscarried babies usually just chicken out at some point because either they're a very sensitive soul and are afraid of returning to this harsh Earth plane. Or, the parents they chose are fighting or having financial difficulties or aren't generally ready to embark on being parents at that time. It's never a judgement and parents should know that in most cases that soul will come back to you.
Reincarnation is a fascinating topic that I could blog about for pages and pages. It was believed in by most major religions until the Emperor Constantine. He was afraid that a belief in reincarnation would negate the belief and faith in the blood of kings. And churches were afraid they'd lose the power of their dangling carrot that promised an eternity of happiness. Still, there are several interesting references to reincarnation in the bible.
So, your great grandmother has most likely reincarnated, but your grandparents are still waiting over there for you.
One of my favorite books on this subject is Brian Weiss' Many Lives, Many Masters.
Please continue to send me any questions you'd like me to blog about. I love hearing from you all!