In 1534 the act of of supremacy passed by the solidified the break from the Catholic church and made the king the supreme head of the church of england. Although there were many reasons for this going back centuries, one that forced the issue at that moment was the Pope refusing to release king Henry from his marriage vows. This was the act that broke the schism and let to Catholicism being less dominant in England.
In this alternate history, I would like things to play out differently. A form of polygamy is allowed, but limited to the noble class to prevent it from going out of control. This would allow Henry to stay married to his barren wife while marrying another who could give him an heir. While this won't prevent the schism by itself, it will by the church some time to set about making peace with Henry to keep Catholicism dominant. However, there are several obstacles to this that prevent it from becoming the norm.
The purpose of an ecumenical council is to define doctrine, reaffirm truths of the Faith, and extirpate heresy. The Pope would have to steer this group into accepting this radically different direction in order for it to become a social norm. By this time, Christianity had a long abhorrence to polygamy, associating it with barbarianism. In the civilized world, it was expected that a man would take one wife. This has been the accepted practice wherever Christianity was present, and any change in this tradition would likely be met with uproar. In addition to this, it is a basic doctrine that both man and woman are equal in the eyes of God. To have separate rights for the wealthy would appear anathema to Catholic faith.
An example of polygamy in Christianity would be some sects of Mormonism. however, Mormons are often considered a fringe Christian sect bordering on heretical, and not wholly accepted by others as a legitimate denomination. I would like to make limited polygamy and acceptable norm while leaving the faith somewhat recognizably Catholic. I also need to limit the backlash as much as possible. Is there a way to make this happen?