Cronos, the only "Trump card" the Orthodox have on this issue is that we have not changed that which the Councils proclaimed, and therefore we know that we have not erred. This leaves the "buden of proof" on the Latin side to show that your addition was theologically and canonically permitted. The Church as a whole will have to determine whether the Latin addition of the Filioque is or sin't an error in that context.
Kolo mentioned many times in the past that a lengthy and learned dialogue between the Latin and Orthodox resulted in a suggestion that it would be best to leave Filioque out for now, even if the Latins believe otherwise, until the General Council can resolve this issue.
I agree, but either way the two particular Churches in the One Holy Catholic and Apostolic Church are working to overcome ecclesiastical obstacles of human nature in order to call such a Council, with the express intention to end the needless schism between us.
The first and most important step is to begin treating each other as One Church, within which there is disagreement that can only be resolved by an ecumenical council. This would be no different that the conditions that existed for the first seven such Councils. Heresy has been creeping into the Church ever since its birth because, after all, contrary to our Protestant firends' belief, the Church is full of sinners rather than spotless "elect."
Our oblgation is to treat each other as part of the same Church first and foremost -- the Church founded on the authority given to the Apostles directly by our Lord Jesus Christ at the Pentecost, and their succession therefrom.
I think it is solomonic indeed. Clearly, the healing must start where the rift began, and so a reversion to the original Creed is logical. Then the Latin Chruch should make a theological case for the dual procession of the holy Ghost, and then a separate case needs to be made to incorporate it to the Creed.
It is possible that the dual procession will end up as a theological hypothesis, rather than defined dogma, even though I personally believe in it and think that Aquinas made a very strong case for it. Most likely, it should be carefully explained with the "through the Son" semantic, which would be consistent with the Damascene's root-branch-fruit image, but preserve the monarchy of the Father.