Data Validation list that can be updated both way

I have created a price book for my use, i have used named ranges as available on data sheet. Th validation is put on price sheet which are criterion dependent.

Now i am trying to find a solution to update the data validation ( data sheet) while entering value from price sheet i.e i should not only be able to choose what is already been updated on the list but could also add on to it without updating it separately on data sheet.

any help..... vba imbedded formula anything that would make my sheet perfect.
thanks in advance.