Is your mother in law with the baby and maid? If you feel your maid is beyond doing things your way then I would replace her. You also need to interview the new maid.
Although it's a headache I feel it's best to replace her before your dear daughter become too attached to the methods used by the maid.
Also what concerns me is that you have explicitly told her how things need to be done and she has ignored you. If this is happening now, will she follow your instructions in 3 months time, 6 months time etc. The longer you keep her the more attached your dear daughter will became making the process of replacing her more difficult for yourself and your dear daughter.
This is rather harsh but based on your post it sounds like you've spoken to the maid a few times already and she's still ignoring you.