Ways that you explained to your little one they were adopted...

I also "practiced" when DD was a baby by showing a "birth book" I put together from when she was born that shows her with her birth mom and dad, sister, etc. with us, with all of us...and then I put in the first days home with us. So I sort of told the "story" in chronological order. Also read kids adoption books to her, etc. That way it's always "known" and it just becomes part of the fabric of your lives and not an "uncomfortable" thing. Best wishes and enjoy that new baby!