I'd love to see them together like this....an orchestrated, top secret performance by Celtic Woman, but filmed with a live audience who have no idea what's about to happen. During the opening song, maybe a new tune similar to the Sky Dawn and Sun, our 'regular' ladies come out one at a time, and as the song progresses, Hayley, Méav, Deirdre, and Alex (at this point, Lisa would be back full time) singing parts made especially for them, and they would finish all together. The rest of the format would be similar, with individual performances, and several with all singing. Or maybe this tune could be at the end, with all singing, for more dramatics!
Oh well, just a thought. It would be fantastic to see them all on stage for at least one song....wow...I can picture it