Doctrine doesn’t change. We view Jesus Christ as the fullness of God’s Word. This Revelation we call public revelation. All doctrines are teachings revealed by Jesus Christ. We can’t add to or change the teachings of Jesus. We do seek a deeper understanding.
We believe in private revelation, those kinds of revelations that guide people to Christ. But none of them are required by all the Church to be accepted. For example, the numerous Marian aparations are viewed as bringing people to Christ. None of us are required to accept them.
Practices can and do change. Practices aren’t doctrines. Spiritual practices, like Bible study, evolve and change.
The Communion of Saints is a doctrine. Individuals being recognized as Saints is not a change in doctrine, it is an expression of the doctrine. Individual devotion to Saints is a spiritual practice.