I've actually given this some thought and done some internet research.
FB- change your profile pic to a jar of Preggo.
Our house is expanding by two feet. (pic of baby shoes with pic of feet of the family)
The {family name} is announcing a system an update! Version 4.0 coming to you in August 2013.
Have youngest child wear a t-shirt that says:
"I'm being promoted to big brother/sister effective 8/13"
"I've got a secret, I'm going to be a big sister"
Or just "big sister/brother"
You can find these shirts cheap on ebay. Under $10.
Family pic with kids holding mini chalkboards saying #1, #2, #3 and then have #4 by your belly.
That's what I have so far. We are going to announce on Valentines day I think.
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