if you are going to feed anything with yoghurt then feed only in moderation as a special treat.I know kaytee do a yoghurt dip treat. Keep at the bean mix,i buy a prepared mix.Certain beans have the potential to be toxic to birds such as,pinto,soy,kidney,lima,black & fava,is is advised to cook these beans first, others soak them for 24 hours.
Pellets arent neccessary but do meet the needs of greys.mine do not eat pellets,but have a human grade seed mix,fruit.soaked pulses,sprouted seeds & veg, so i know that i am meeting their dietry requirements.
i have includeed some links for you to have aread through..
http://www.greyforums.net/forums/bird-food/53831-tips-for-getting-your-grey-to-eattry-new-foods.html
http://www.greyforums.net/forums/bird-food/59809-complete-veggiefruit-list.html
http://www.greyforums.net/forums/bird-food/28994-do-you-sprout-.html#71335