Zebra Finches Stopped Sitting on Eggs?

I have had a pair of zebra finches for 2 months. They were in a much smaller cage. I shift them to a bigger cage and provided a breeding pot and nesting material. After a while she laid 2 eggs. Both the male and the female take turns sitting on them. 1 of the babies died while hatching and one of them survived. When the baby bird came out of the nest the female had already laid more eggs.

Both the male and female were incubating them. I provided an additional breeding pot and material for them. They build half of the nest then stopped. 2 days ago I noticed there were really small insects coming out of the nesting pot. There were so many of them. I took out the nest and washed the pot and put some new nesting material in the pot and all 4 of the eggs. I never touched the eggs I handled them with a tissue paper. And I put the nesting pot again in the cage. This took hardly 30 minutes.

The male quickly jumped in the nest and the female was going in nest looking at the eggs, but not sitting in them. The next morning I saw that they were building another nest in the new pot, but also checking up in the old pot looking at the eggs. Then they broke 2 of the eggs. They are still making a nest in the new pot, but not throwing the other 2 eggs out and are not sitting on the eggs, but are checking up on the eggs. And they sleep in the old pot. It's confusing! Help.