As well as the Abba songs, each act is singing a 'Song that will get them to the final' a.k.a tenuous reason to just sing anything.
And I think Robbie is back. Have we missed him?
Girls
Scarlett Lee
This Is Me by Kesha
Winner Takes It All by ABBA
Groups
Acacia & Aaliyah
Blinded By Your Grace / I Win by Stormzy / Lethal Bizzle
Money, Money, Money by ABBA
Overs
Danny Tetley
This Is My Life by Shirley Bassey
Thank You For The Music by ABBA
Boys
Anthony Russell
Livin' On A Prayer by Bon Jovi
Name Of The Game by ABBA
Brendan Murray
Run by Snow Patrol
I Have A Dream by ABBA
Dalton Harris
Feeling Good by Muse
S.O.S. by ABBA
A mixed bag- I think Dalton will have a good stab at 'Feeling Good' (not really sure why it is attributed to Muse, the arrangement is very similar to the original on their version).
Simon might be sulking, but 'Winner Takes it all' could be a, erm, winner 
I can't stand TTT or Bon Jovi, so that's a no, and Brenda is going end up sounding like the Westlife version of 'I had a Dream'. Only as if a breathless little girl was singing it. (I hope he gets a stool for the key change ).
I need lots of snacks.