I traveled to & from UK - Spain this spring on Ryanair on crutches, unaccompanied but having contacted Ryanair beforehand to ask for special assistance (or whatever they call it). As I remember, I did this by going into their chat facility either under 'contacting
Ryanair' or via 'manage my booking'. The chat facility isn't always available (not sure if it's only 'on' between certain times or based on staff availability- I had to try a few times before it was available - it's done via you & the staff member keying
in on your computer screen. At one point they weren't being very helpful so I keyed 'maybe I'd do better to just cancel the flights' & they went away to chat with their co-workers & came back to offer exactly what I needed. As your daughter will be accompanied
anyway I can't see why there should be a problem but, with Ryanair, it's better to check beforehand - and send a copy of whatever Ryanair agree to your daughter/her companion in case local staff query anything (you can get a copy of your chat & print it off).
Good luck & I hope your daughter's injury heals well & quickly
It's 'Ryanair online chat service'