Please talk to a vet about the smelly poop - that's not normal for birds and could indicate an infection. It could just be due to the diet (and hopefully that's all it is) but it could also indicate something more serious.

A bit part of my birds' diet is Harrison's pellets. They make a version with small pellets for cockatiels, you might try feeding that to your birds and see if they like it. Some bird stores carry it and I think most bird veterinarians also sell it.

Nate Waddoups
Redmond WA USA

As Nate said, basically in a healthy captive parrot fresh excrement is odorless with two exceptions. Birds consuming high animal fat diets (e.g., meat, chicken bone marrow or fried foods) may have a rancid oil odder for several weeks even after you change the diet. Also pasty droppings adhering to the vent and produce a metallic offensive order are frequently seen in cockatoos. These droppings usually have a high PH. Any thing else is considered abnormal and symptomatic requiring a vet visit.
Mike Bross
Phoenix AZ