I have been switching my budgies, Thistle and Ivy, from a seed-based diet to Harrison's pellets. They have been doing really well and I have been able to slowly taper down the amount of seed to a minimal amount. They have been eating all of the pellets and seed that I have been giving them daily.
I bought a new bag of Harrison's (the same type as before) and started giving it to them two days ago along with the small amount of seed that they still get. The first day that I fed them from the new bag, there were pellets left over in their feeder, but they ate the seed. I thought that maybe I accidentally gave them too much of the pellets. This evening, however, I noticed that today they ate all of the seed but none of the pellets.
Has anyone else had this experience with a new bag of food? I am going to contact the vet in the morning and see if they can replace the food. In the meantime, I gave Thistle and Ivy some millet and extra seed, since they need to eat something.
For now I'd still offer the mix of pellets and seed. You might then try putting just pellets in the feeder until noon and then all seed in the afternoon. If the taste is a bit different,(maybe fresher) the pellets may seem foreign and not as acceptable as the seed. Birds can quickly sort out what they like so, once they accept pellets is usually best to feed straight pellets and offering seed separately every other day for variety. That's what I do with Steve, and he's always been healthy and enjoys both (but separately on different days).
Your budgies should each be getting 1 1/2 to 2 teaspoons of seed daily.
I recommend you ration the seed into morning and evening servings and keep plenty of pellets in their cage 24/7.
By rationing the seed and giving them only their allocated amount of seed each day, they are encouraged to eat their pellets whenever they may be hungry throughout the day and the seed is not available.
I never mix my budgie's seed with their pellets. They have separate dishes for the pellets which remain in the cages 24/7.
A healthy diet for your budgie includes pellets, a high quality seed mix, vegetables, egg food and occasionally a bit of fruit as a treat. (Fruit should only be given sparingly due to the high sugar content).