I'm sorry for not being active on the forum lately.
Anyway, I decided to take your advice (the same advice of my vet) and convert my budgies' diet from seeds to pellets.
I bought the pellets yesterday and I sprinkled some of them in the seed cup, but the budgies obviously ignored them (I know it takes a lot of time), so I decided to give them the pellets with my hands.
Celeste, who is four months old, immediately started to eat them and, while she still has to learn how to eat them, I can say she likes the pellets.
Unfortunately, it wasn't the same with her parents, Sid and Stella. Sid accepts food from my hands, but when I offered the pellets to him, he refused to eat them and now he bites me everytime I do it again.
Stella is not tamed at all, so I didn't even try to offer the pellets to her. But if Sid starts to eat them, I'm sure she will too.
My only problem is that Sid is at least 6 years old (I bought him on August 2014 and, on an Italian forum, they told me, looking at his photos, that he was more than a year old), so he is a little old and I think he, just like an elderly person, might not accept to change his habits.
Do you think It is too late for him? Or could he learn to eat pellets after eating seeds for at least 6 years?
Thanks in advance!