Throughout my career as a speech pathologist I have worked with children with varying degrees of nasality. Some were purely functional and responded well to therapy and others I referred to an ENT for evaluation for possible surgery to correct abnormal structure. My earliest experience was on the Cleft Palate Team at Northwestern University Hospital where a team of doctors and speech pathologists evaluated patients. Working in the schools and now in private practice I occasionally have a child who is hypernasal and needs therapy.
My current client is 3 years old and hypernasal on specific consonants. I found the following article by Ann W. Kummer, PhD, CCC-SLP on Speech Therapy for Characteristics of Velopharyngeal Dysfunction (VPD) to be very helpful, distinguishing between abnormal function and abnormal structure and when therapy is appropriate. She gives activities to encourage auditory, visual, tactile-kinesthetic and tactile feedback and activities to increase oral pressure.
Let me know what resources you have found to be valuable in treating children with velopharyngeal dysfunction.