Does yibum cause a marraige d'orysah and a get is required d'orysah or is a get d'rabbonon and d'orysah no marraige takes effect via yibum d'orysah, and only the first beah is d'orysah?
yehuda, usa
Min ha'Torah, Yibum alone acquires the Yevamah completely. Should her husband subsequently wish to divorce her, he will have to give her a Get.
Over and above that, the Chachamim instituted that if a Yavam gives the Yevamah a Get, he is forbidden to marry her relatives and she is forbidden to marry his, as if he had divorced her. In addition, once such a Get has been given, he or one of the other brothers, is obligated to perform Chalitzah (min ha'Torah), to remove the Zikah. The option of Yibum no longer exists (mid'Rabanan).
Be'Virchas Kol Tuv,
Eliezer Chysler