However, one not entirely unanticipated problem is re-introducing those characters when the main character is no longer meeting them for the first time. My main character has a very complicated family relationship and I don't want to constantly be slowing everything down to explain exactly how somebody is related to him.
Briefly, in another world view, my main character would be considered a bastard. His actual father has four legitimate children and several other illegitimate ones. Only one of those will be important, though. That's five half-siblings on Dad's side. His mother married and has two children by her husband, for a total of seven half-siblings that will figure in the story. The main character was raised by his step-father and he calls both his real father and his step-father 'Father'. Fortunately, they live some distance apart and he's rarely around both of them at the same time.
Add to all of that, the main character is married for the second time himself and has two children by his first wife. Yikes! It'd take me a chapter just to sort out who's who for a reader.
So, what I'm wondering is what about the idea of having a sort of family tree in place of a prologue? Sort of a cheat sheet for readers to go back and see how everyone is related. This would not be a substitute for introducing the characters. More a sort of visual aid. Altough it might take some of the pressure off the initial introduction and let me ease into it a little more slowly.
As to meeting previous characters. you introduce them as you would in a single episode story, just write it so they are familiar with each other. You then include information about them about the past as it is necessary.
One series that did this well was Anne McCaffrey's PERN series. Each story was about a different character, but previous characters were introduced in the stories as needed.
I do like this kind of series wehre you don't have to read the first book to enjoy the entire series, but of course, reading the series makes it even better.
I remember OSC doing this type of exposition in Speaker for the Dead when introducing Ender. It might not be a geneology, but the character's background is important to the story, and the author can't assume the reader has previously read Ender's Game. Working it into the story, either through characters' perceptions & expectations that leave some things unsaid, or through direct exposition, will always be obvious to some readers, but seems to be the most common approach I've noticed. (Though, maybe because I've *noticed* it, it isn't the best... proving I don't really know )
I'm just not all that into prologues (go figure).
I don't think the genealogy is necessarily a bad idea, but I think the text still needs to speak for itself without it. My approach would be to write, then go back and examine each relationship with an eye to how crucial the exact nature of the relationship is, and add exposition where it is most needed.
I think a diagrammatical family tree would work well for you. That frees up some of your prose from having to explain every relationship in detail, however you still must define relationships in the story where they are germane to the plot.
I view it in the same way I am always appreciative that an author has put in a map to track where the characters are and where they are going.
Knowing Volume 1, it should work just fine.
I may have to do another, slightly more complicated one, for the start of Book Three. But I'm not there, yet.
As for whether it goes in the front or the back of the book, that'll be a decision for the publisher (she says confidently, sort of).