I do agree with Ênio's guesses, but I have other ones:
Dawning of the Day: Chloë, Megan, Muirgen and Tara
Bonny Portmore: Megan
Mise Éire: Chloë, Megan, Muirgen and Tara
Wild Mountain Thyme: Chloë, Megan, Muirgen, Susan and Tara
Beeswing: Muirgen, Tara and The Longest Johns
Down by the Sally Gardens: Chloë
Where Sheep May Safely Graze: Tara
Angel: Chloë
The Lakes of Pontchartain: Megan and Tara
May it Be: Susan
The Calm of the Day / The Banshee: Tara
The Galway Shawl: Muirgen
Black is the Colour: Chloë, Megan, Muirgen and Tara
I do not see the point of Susan being featured in the album and not be a part of a group number. I could be very wrong though, cause implying that Susan would be featured in a few or none of the concerts, would compromise a group number on tour... Let's wait and see