New Female Finch Not Sitting on Eggs Laid by Previous Female?

I had 2 Zebra finches, a male and a female who bred and laid about 6 eggs. The female cared for them really well. However, unfortunately my female finch escaped the cage and the male was left to care for the eggs. In a panic I got another female zebra finch hoping to save the nest. However she does not seem to be sitting on the eggs during the day, only during the night. (I guess to sleep.) The male goes back and forth constantly to the nest, but usually to continue to build the nest.

They are due to hatch any day now and I'm wondering if she would care for the chicks at all? Either that or would she lay new eggs in the old nest with the last batch of eggs still in it? I ask only because the new female finch has already started to mate with the male finch I have. Any answer would help as Google doesn't provide much information.