Hello. I also have adopted children, 6 in fact! Before entering this lifestyle, I read many books and talked with many adoptees from various ages, backgrounds, and stories. My suggestion is to NOT lie. Silence is easiest on us parents, but can foster a sense of being lied to as the child grows older. I have found that if I use an attitude of acceptace and relaxation, my children mimick that attitude and we are able to have open conversations about their 'previous life' frequently. They do not need to hide their feelings from me, and I am able to help love on them through their experiences. My elementary age children remember well life before my home. The babies (age 12 and 26 months) do not have any prior memories, but I still tell them their story of joining our family at least once a week as a bedtime story. The 2 year old loves to hear the story about when I met him at a McDonald's.
Because I do not personally know the kiddos bio-family, I allow the big kids to share their memories with the younger kids. Some stories are happy, others heart-wrenching -- but that is what they remember. I hug them and we pray for their bio-family together. I tell them how much I admire them for their strength to walk this difficult road. I LISTEN for hours. And I hug lots! Open communication is the key.
The facts is you will have to deal with this eventually. The younger this is presented, the less negative reaction you will probably experience. A 6 year old is old enough to understand love, loss, lies, and also forgiveness.
My advice is to tell her a bedtime story about a young princess who you met and fell in love with, and who is the light of your life! No need to focus on the horror of the tale, but the love from you. Start with the story of your lives together (meeting and adoption). Tales of the bio-family will come soon. Tell her when you can sit with her and allow her time to process this without having to run-off to something else... Friday night before a quiet weekend at home maybe.
I will be praying for you as you enter a new relationship with your daughter. Remember, it doesn't HAVE to be a scary story filled with hate, drugs & loss -- it can be a beautiful love story too!