Henrietta, Matilda and Florence (Hettie, Tilly and flossie)
Henrietta, Matilda and Jessica (Hettie, Tilly and Jessie)
Henrietta, Matilda and Sebastian (Hettie, Tilly and Sebbie)
Henrietta, Matilda and Thomas (Hettie, Tilly and Tommy)
You could also have names that have an e sounding ending that aren't shortened....
Phoebe, Evie, Ruby, Lily, Poppy or Jamie for girls
Toby, Coby, Cody, Albie, Alfie or Jamie for boys.