seems that she is not so bad. the next step is, you have to find out if she is willing to take care of another baby. they can easily find a new job.
i also talked to my maid very openly that i had a plan for another baby. i didn't offer her anything special (such as salary increase) but just told her the baby would come when my elder daughter started K1. if she was not willing to renew the contract, i would let her go.