mkwok,
I had a very similar situation as yours. My boy is now 13 months old, and my old maid was just fired because she did not take good care of my son. My old maid was a yan yan. She was with me before my boy was born. However, after I went back to work after the maternity leave, she always left my baby in the crib / playpan, without playing / talking to him. She always talked on the phone, or even went out. My boy was like an orphant, always bored and doing nothing.
So, although she knew really well about my boy, I finally decided to fire her as I think the first few years of life of my boy is very very important to his future development.
Now a new maid has come, and my boy is still adapting to her. I took 2 weeks leave to train up the new one, and I found it's essential.
Back to your point - whether it is hard to adapt. I think it all depends on the bonding between you and the baby. Like me, I sleep with my son and I spend all my time with him during holidays / off work. So he used to be very close to me. So my case is not that difficult.
"add oil". A bad carer is really no good for the baby, especially young ones like ours.
我鐘意你同我講 I Love U, I Love U Too!
You are the sunshine of my life. That's why I'll always stay around. You are the apple of my eye. Forever you'll stay in my heart.