Plotline...ok -others please cut and paste and add bits:
The School at the Chalet - The Chalet School in Exile
The Tyrol years, Madge is head and the marries Dr Jem. Joey progresses through the school heading up as head girl. Juliet, Grizel and of course the magnificent Gisela Marani are head girls during this point. Also Mary Burnett, Biddy O'Ryan and Hilary Burn who both later return as teachers. Bill, Charlie and the Abbess all join the school to teach. Mademoiselle is Head before becoming very ill. Eustacia, Cornelia, Evadne , the Lintons and Elisaveta are all feature. This section of books ends with the Nazi takeover of Austria and the flight of several major characters in to Switzerland.
The second part of Exile and teh Chalet School goes to It are the Guernsey years. EBD sent the school there and then when it too was invaded she had to decamp again.
During this time Joey (who has married Jack 'off screen') produces triplets and there is an enormously moving reunion with Frieda who has escaped the nazis too.
Thence follow the Welsh years including Gay from China at the Chalet School, Lavender laughs at the Chalet school and many others that I can't remember. The school is in Wales. Joey has three boring boys during this time. The school then moves to an island off the coast of Wales and teh last few welsh books are set there - Peggy of the Chalet school. both Peggy and Bride are head girls.
Then the school goes back to Switzerland - Changes for the Chalet school - and the books conclude with about the last 20 or so books? In this time Joey produce Cecil and twins Phil and Geoff, the triplets grow up and Len becomes head. Madge is not much seen and Eyropean characters - hardly seen in the Welsh books again assert themselves.