Changing their diet to more meat will help the dandruff. You may want to check into a supplement from Dinovite, I know several people that have their pets on it and it does wonders for their skin and coat.
How Can I Remedy Dandruff In My Cat?
Give your cat a good bath and haircut, and feed her more tuna. There's a step by step guide here www.catdandruffaway.com
You can remove your cat's dandruff by yourself at home. To follow the complete instructions, click on the following link.
Cat Dandruff Remedy
Cat Dandruff Remedy