1. Dignitas Personae (DP). Published in December 2008, this is the only Vatican issue document that mentions embryo adoption (see sections 18 and 19 specifically). While the wording is strongly negative, it does not label EA as illicit. The Church knows how to be clear; there is no room to question her ruling on IVF, for example. However, she has specifically chosen this somewhat ambiguous wording on EA for the time being.
Side note: shortly after the Vatican released Dignitas Personae, the United States Conference of Catholic Bishops (USCCB) issued a short Q/A and summary in response. While many theologians were questioning the openness of the EA debate following the release of DP, the USCCB's Q/A clearly indicated that the debate was still open. (See page 3, question 5).
2. While the National Catholic Bioethics Center (NCBC) was predominantly against embryo adoption, they did recognize that DP left room for personal interpretation, or "further theological reflection" as they put it.
3. In November 2009, the USCCB released "Life-Giving Love in an Age of Technology". This is the ONLY time that the Church has mentioned embryo donation and embryo adoption as two separate courses of action. I wish the document actually defined the two and clarified their differences. I have my own ideas and perhaps one day will finish my draft and publish it, but I digress... Page 12 specifically mentions embryo adoption as morally concerning, while egg/sperm/embryo donation is clearly condemned on page 5.
4. If you want to get a feel for some of the differing schools of thought on EA, try to locate a copy of The Ethics of Embryo Adoption and the Catholic Tradition. I first read this when a med school friend checked out a copy for me from his school library in 2008 or 2009. And then I was blessed to receive a complimentary copy from the editor. Though the compilation predates the release of Dignitas Personae, many of the arguments remain the same.
5. Ronald Conte is a Catholic moral theologian. He wrote a lengthy essay arguing on behalf of the theory of embryo adoption. I do take issue with his specific proposal for thawing/transferring (only a single embryo at a time), but that should be saved for another blog post.
6. I first "met" Dr. Gerry Nadal through his blog, actually his first installment on his embryo adoption series. We even talked on the phone around the same time he wrote his three part series. I'm pretty sure I was the first person with whom he'd interracted who had real-life experience rather than just theoretical experience with EA. Click here for Part One, here for Part Two, and here for Part Three of his series on embryo adoption.
7. There is a blog called "Catholic Moral Theology" that is written by a "group of North American Catholic moral theologians". In January 2013, they published a piece that examined embryo adoption from a different standpoint. "Setting the Captives Free”: Is There Precedent for Embryo Adoption in Scripture and Medieval Christian Tradition?
This is not by any means an exhaustive list. Since I personally am arguing on behalf of embryo adoption, many of the links above argue the same. Just keep in mind that support for EA is in the minority among groups of "professional moral theologians". If you do a little internet digging, you will undoubtedly find a long list of articles against EA, if you so desire.