With the events going on in Jerusalem right now, there are a lot of things being discussed related to ecumenism. The below is a link to the Latin Church's position on the ubiquitous term "Sister Churches."
Written under the oversight of Cardinal Joseph Ratzinger (now Pope emeritus Benedict XVI), Prefect of the Congregation for the Doctrine of the Faith, this document was approved by Pope John Paul II (June 9, 2000).
Highlighted below is an ecclesiological perspective often absent in careless, ecumenical discussions (both East and West), and is a helpful corrective to radical ‘ecumenists’ who would deny the basic foundations of Christianity; that is, that Christ has established one holy, catholic, and apostolic Church, and that the gates of Hades will never divide it (Matt. 16:18)...
Read the rest on the blog On Behalf of All here.