Tarkine,
I just read the rest of your post that's a tough situation I'm not really sure how the best way to handle it would be? we were lucky that DS wasn't an issue for any member of our families (well not that they have told me) I'm sure your bubba will weave his/her own spell around grandma eventually, I don't know about having her at the birth that is a fairly personal choice I guess, I was adament that I only wanted DH at the birth but my SIL on DH's side works at the hospital and some how she managed to make her way in in the last stages of my labour I think it was the timing of the question put to me during a couple of close contractions it went something like "is it ok if ..comes in" my response was "I don't caaaaaaaaaaaaaaaaaaaaaaaaare!!!!LOL or words to that effect, when it came down to it I didn't mind.
next PG my other SIL on DH's side will be invited to be there for different reasons, she has been having her own infertility battle at the same time as us but unfortunately things aren't looking that great for her now so I want her to share my birth if she wants to.
sorry I'm not much help hopefully the others will have some ideas for you