I thought there was another similar thread not so long ago, on the lines of “songs to sing in care homes” (and such places as day care centres for the elderly and dementia groups.). Any of us who have done this will recognise this phenomenon of people who are possibly non-verbal even on a day-to-day basis, suddenly joining in with songs from their youth that are being sung.
And yes, Helen, songs from either of the world wars are definitely out!