I've got a vocal chamber group with 3 female voices (2 x soprano and 1
x mezzo/alto but we're flexible)

Looking for classical repertoire - either operatic or chamber. A
variety of different styles and eras, both accompanied (piano) or a
capella.

Could you provide a list of suitable repertoire. We already have:

Mendelssohn Elijah - Angels trio
Bizet Carmen - Gypsy trio 
Strauss - Der Rosenkavalier - Octavian, Sophie and Marschellien
Mozart - Die Zauberflote - Three Ladies, Three Spirits/Boys

This is for concert performances and assessment (university) in about
10 weeks so they need to be pieces that can be prepared in about 8
weeks of rehearsals (3 hours per week)

Cheers

Kathleen

Have you considered 'Sing For Your Supper' by Rodgers & Hart?

It's a super piece for three good female voices and was given a
brilliant jazz treatment when first performed on Broadway.

It was a real show stopper!

How about "Three Little Maids from School" from "The Mikado" by
Gilbert and Sullivan?  It's delightful and challenging.