The Vowel Family A Tale of Lost Letters by Sally M. Walker illustrations by Kevin Luthardt

Pm Smth and Sm Vwl married but talking was difficult.  So this couple has twins (Alan and Ellen, then Ellen, Iris and Otto) which makes talking a lot easier.  Sometimes their aunt Cyndy joins in the family fun.  The actual words in this story are missing the vowels until the representing vowel character appears permanently on the scene.