Eileen - Bitter Sweet Symphony by The Verve. Bitter sweet sums up Eileen’s attitude towards the Kingdom.
Eileen and Jenny - Calling Occupants of Interplanetary Craft by The Carpenters. The last thing Eileen or Jenny want to do! Eileen especially has seen enough strange beings to last her several lifetimes.
Eileen and Derek and Jenny and Paul - It Takes Two by Marvin Gaye and Tammi Tyrelle. One for Eileen/Derek and Jenny/Paul.
Roxannadrell - Killer Queen by Queen. Obviously applies to Roxannadrell when she kills the Witch. Can also apply to the Witch when she briefly takes over the realm.
The Queen's view of Eileen's behaviour over Derek - The Lady is a Tramp by Frank Sinatra. What the Queen thinks of Eileen for falling for a mere human!
Eileen - My Way by Frank Sinatra. An obvious one for Eileen, possibly too obvious. One she’d enjoy on the quiet because of that.
Eileen and Derek and Jenny and Paul - Good Vibrations by The Beach Boys. Ignoring the obvious sexual links here for Eileen and Jenny with their spouses, it can apply to the women and the fairy squad when detecting spells cast and those responsible for them. Pity there isn’t a song called Bad Vibrations for when they’ve discovered the Witch has been busy!