You never know, the (adult) child might be looking for you too!
Here is a link to a registry that helps connect adoptees with bio-families.
Doesn't matter if one is a parent, grandparent, sibling~doesn't matter if it was a "closed" adoption... it's just a registry.
You put in all the information you have, they enter into a database, and you wait to see if there are any matches. It may be only one detail that ultimately makes the match! They have a lot of success stories. Best of luck to you in this search.
The ALMA Society

Many thanks to dontknownuthin, J-9, and Synnen for their close experiences and eloquence in the matter of adoption.
I bit my tongue so hard on the topic of how your teen daughter was treated!
I didn't want to get embroiled in two topics, but after reading the above, I too want to vent.

"I interpret the Bible to say a parent should excommunicate a child who is too wayward."
OUCH! Where are you finding this, and why are you side stepping the parable of the prodigal son?
How is it that you can say that she had and apparently still has mental issues, yet you then call her a 'bad apple?'
And a comment: There is always the possibility that a child who lies about being molested by her father, something most would find too alien (plus having to face the father she's charging), made that lie out of tiny truths. Her father was gone a lot, and may have come home and said something about her developing, or acted in slightly uncomfortable ways, or he just seemed like a stranger who didn't love her. And if you were unapproachable for mother daughter talks, and she had no siblings, where does she turn? That may have led to her promiscuity, which you seem to have been totally unaware of.

Let's say you do finally meet. She doesn't develop warm and loving feelings towards you, and decides after hearing that her mother and you are estranged, actually feels sorry for her mother, even though her mother wants nothing to do with her, and blames you for the fact.
So she decides to strike out at you. And she becomes the only scammer of your money, out of all the people in the world who could scam you. Is that a scenario you thought of? There are countless, of course.

After you explained more of the history, it had the opposite of your intended impact for me. Far from sympathising with your position, my heart goes out to your daughter.

First, if you're going to do something as horrible as to disown your child, please at least learn the right word for what you've done. To excommunicate an individual is to toss them out of the Christian community. On who's authority can you determine that your daughter cannot be Christian, will not be welcomed by God one day? And what mother would claim to be a Christian while justifying her weirdly inflated belief that she could cut her daughter off from Christian faith and God? God will receive your child whether you want him to or not. You might have a few hurdles to get over in reaching him yourself though. You abandoned your daughter in her darkest hour.

I also am not convinced by these "testimonials" from third parties that your daughter was not molested. You describe a counselor who apparently grilled your child over inconsistencies in her abuse story, which would not likely happen. It is actually fairly common for abused people to remember some details wrong. Your daughter's behaviors certainly are consistent with actions of an abused young girl. Many, after being sexually abused, do act out sexually. In fact, I have read many studies which concluded that sexual abuse is behind the actions of most children who seek sexuality well before their same-aged peers. As for all these testimonials to your husband, I'm not convinced. In fact, it appears you launched a campaign against your own daughter which makes me wonder what you're hiding that you do not want to face. You're acting like she's some outside third party, an adult, making wild accusations. She's your daughter and instead of casting her out, your job was to support and help her. Even if her stories were truly lies, there is a truth beneath them that you obviously don't care about - something happened to her and her mother doesn't give a crap.

You threw away your daughter, so now leave her alone. You have zero right, none at all, to her children. None. If you want to be part of her children's lives, it is only with her consent.

What's more, your judgement against her as a "liar" because she tells people she has one child and not two, is childish and ridiculous. She place her first child for adoption and it's a very private matter. She doesn't want you to know about it because you're aweful to her and only compound her hardships - what use are you to her? You aren't interested in her wellfare at all. Your own mother recognizes how aweful of a parent you've been, so she's not fessing up about it either. You forfeited your parenting rights to this daughter, so live with it now - her life and her children are no longer any of your business.

Now, you haven't done enough manipulative damage, now you think that you're going to save the psychie of someone you don't even know. Not all adopted children want to even know anything about their biological families. They don't want any information shared with them even in the process of finding out if you want a meeting. What's more, there is probably already communication established between your daughter and her child and the adoptive parents. It was pretty much the norm by 1991 that some openness existed such as letter and photo exchanges, in case the child should ever want a reunion as an adult. That known, your grandchild could find you if she wanted to.

You sound like a person who, no matter what others have to tell you, doesn't listen and doesn't seriously consider as valid any opinion other than your own. You've had countless people tell you now - all of us with experience in adoption - that your plan is a loser and will hurt people. That doesn't matter though - it's all about you.

Sorry to sound harsh, but I'm so angry that a mother would throw out her young teen daughter, I'm just beside myself. Raising teenagers is hard for all of us... there is not a teenager in the world who is always easy to raise. Yours was in distress and so lonely and lost that she was putting herself in dangerous situations, so what do you do - amp up the problem by throwing her away. Now you think you have a right to HER children? Not in a million years. And you're judging your daughter and your mother for giving the child away for adoption? They made a loving plan for her child. Compared to you treating your child like yesterday's trash, I think they are way ahead of you in the line to heaven.