Eastern Rosellas

We have been casually watching (when possible) the first clutch Eastern
Rosellas have produced in the nesting box attached to our shed wall. The
clutch started as 5 eggs and the only chick hatched on, or about, 9 Oct. By
23 Oct there was one growing chick and 2 (presumably infertile) eggs and
some egg shell. But to our surprise on 28 Oct (chick now 19 days old) 2
more eggs had been laid. ie one chick and 4 eggs. The 4 eggs included the
old, stained infertile eggs and 2 new white eggs.

I have done a little bit of a search and can find no reference to Eastern
Rosella females laying whilst there is still an unfledged chick in the nest.

Has anyone seen this or seen reference to this happening?

Thanks Geoff