What did the Vatican ask Marcel Lefebvre to do to regularize his society? Read the Protocol he signed with Ratzinger on May 5, 1988. It had provided the terms under which a bishop could be consecrated for the Society–but it was quickly recanted by Lefebvre and he went ahead with his own desire to ordain four rather than go along with the agreed upon plan to ordain one.
Here’s a webpage with a brief sketch of the history.
Is the 1988 Protocol back on the table? No one has said.