Why do womanly cockatiel hurt mate couple?

My cockateil is mating but this other one will not let her sit on the eggs she just blocks the door and i know she is not the other mate bird.Will she hurt the other female's egg should i take her out please help me
I found a bird. Is he sick?
Answers:    Mating pairs should have their own round up & other birds should be removed.

You risk injury to the birds & destruction of the eggs...also the hen that is laying will lay 4-6 eggs, so yes, take the other bird out.

Good luck...
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