Hi, Phil. I personally believe that nope, not at all. It is all about the upbringing--say there is a great possibility of spoiling your child by giving him or her too much of what he/she really needs and more of giving into what he/she wants. And having a helper is certainly not part of what your child really wants in the first place. Instead of worrying about that, I suggest that in order to prevent your child of getting spoiled, you should talk openly to your child about behaviour--set age-appropriate boundaries. Say if you still have a toddler, you can tell your tot on things that he/she should not do or giving him/her just the right amount of food that he/she needs. And be consistent. In this way, you are not overindulging him/her.
I don't think so. It depends on how you're raising your child and how the yaya treats the baby. Just make sure that you let the yaya know your do's and don'ts .