Good morning Girlies02 :)
I read through all the responses and I bet you're asking yourself, "Why the heck did I ask people to weigh in on this? Why did I even bother asking for advice?" (lol) I myself have found that sometimes when you ask questions 'on here', all you get is JUDGEMENT instead of the "good advice" you were seeking! (Not all the time mind you, but many times... :)
It's a shame and I don't know why people do it, but I sometimes wonder if they're reading a post left by someone who comments and these readers just assume that it is your thinking and/or beliefs!? Go figure! All I know, is that it's been done to me as well when I've asked questions. Some people totally misconstrue or twist things around and don't even address your "actual" question.
Also, I'd just like to say, I didn't think you came across as judgemental at all. I felt like you were legitimately concerned for the mental well being of your two daughters and/or how they were going to process this, especially since you've always told them that "God gives babies to couples that are married." To me, it just seemed like you were looking for a way to resolve or reconcile what you had previously said... :) You were looking for some good advice, not judgements and/or people pointing fingers or faulting you.
I guess that's the way of the world today... everyone thinks they would do things soooo much differently; however, NO ONE knows how they would react, until they themselves were confronted with a situation such as yours.
From experience though, I have a 4yr. old who has an older sister (my step-daughter, who lives w/her mother). Anyway, her older sister had a baby out of wedlock at 19 yrs. old. My daughter NEVER questioned her age or whether or not she was married. She just 'assumed' (and we let her) that the baby's father was her sister's husband. All my 4 yr. old was concerned w/was how did the baby get in there and how is it breathing, why is it soooo big.... those kinds of things.
She didn't even recoginze that her big sister was only a teenager and that she wasn't married. To my daughter, everyone who is "bigger" than her, is an adult and everyone who has a boyfriend, is married. The only concern I had at the time, was that my daughter started putting her dolls under her shirt (mimic'ing) pregnancy... I wasn't exactly sure how to address that (lol)
In any case, I just try to be as truthful as I can when she asks questions that may be complicated and/or about delicate issues. I try to explain in terms that a 4yr. old will understand...
Like recently, we had some issues with the "death" and I've never really wanted to cover that issue w/her at this age, but since she's questioning it, I just tell her what I believe about God and Heaven and people (or animals) staying with us in thoughts and spirit.
I haven't tried to cover it up or make it less than it is, because there will come a time when reality will set it and I don't want my daughter to think I fed her a bunch of hocus pocus or lies. I don't want her to be blindsided or traumatized more, by what I "didn't" tell her, rather than what I "did", ya know?
To me, you can talk with your girls about whatever YOU feel is appropriate, based on your family's values and/or morals. To be truthful though, they probably won't even think about the things you're concerned with, so maybe you should just wait to see what they have to say and then go from there.
Well, here's to wishing you and the family all the best, and that goes for your babysitter as well! I hope it all works out :)