My son had the same thing happpen to him at the age of 5. After being on Adderall for a year and a half he started to clear his throat almost constantly and didn't even realize he was doing it. I was told this was caused by the stimulant in the Adderall. His doctor called it a throat clearing tic. He was taken off of the Adderall and placed on clomid. This took away the tic but didn't work well for the ADHD. He now takes Metadate CD along with Risperdal. He no longer has the tic and has been on this combination of medication for over a year now.
Chronic throat clearing can be associated with mild asthma, a good possibility in a household of 8 smokers.
I agree, second opinion time.
It sounds like you're not in agreement with medical decisions reached about these children. Arrange for a second opinion if you are not comfortable with what has been decided.