That's what the Churches are actually doing. Our differences are very clearly defined. They involve both theological and ecclesiastical issues. As of last November, the Churches are working on the subject of Petrine ministry and the extent of its authority. Although not much is heard about it over the media, a lot of work is being done on one of the most important issue: extent and nature of papal authority. Without a consensus on this, no reunion attempts can even begin. Once, hopefully, this is agreed upon (this may take decades!), the Pope can call an Ecumenical Council which will then address theological issues (which may take a lot longer).
So does communion come before or after an Ecumenical Council?