GoodToBetter
I think you are making progress but you still have a long way to go.
As I stated before she has trained you your whole life to do her bidding.
The malignant narcissist is still a malignant narcissist even after you give birth. The fundamental nature of your malignantly narcissistic parent is the same as it was when you were a child. (If not worse.) Due to no reason other than the fact that you brought a child into the world, your narcissist parent is now a narcissist grandparent. Your bringing new life into the world did not fundamentally change your abusive parent into a loving family member. But adult children of narcissists (ACONs) seem to show a natural affinity for believing in this work of fiction. We have always wanted our parent to be loving to us, and now we want our parent to be a loving grandparent. What we want and what we end up with are two very different things. Where we usually get tripped up is our failure to recognize the adaptability of the narcissist to changing circumstances.
It is highly unlikely that your NPD parent will interact with your children in exactly the same way they did with you. At least, not in your presence. They have adapted their methods to the new situation of you having a family of your own. They know they don't have the same power and control they used to so they usually switch to sneakier methodologies. Which allows you to think that they have changed from what they were when you were growing up. From my personal experience, and from observing the experiences of others, the NPD grandparent will use their grandchildren in the same way they would use an inanimate tool. Without regard for the humanity of your child, that child becomes a tool in the hand of your NPD parent to hurt you. This will always result in moral and/or emotional harm being done to your child as well.
The actual mechanics of how the NPD grandparent will misuse their relationship to their grandchildren will vary. Generally, they will either over-value or under-value the grandchild as a means to get to you. Often, when they over-value, it is the objective of the N grandparent to steal the child from you. I mean that in both senses, physically and emotionally. Ngrandparents are known for so much trash-talking against you behind your back to your own child or children that they want to go live with grandma or grandpa, or the N grandparents simply inspire rebellion of the child against you. They steal the hearts of the grandchildren. Sometimes, they will battle for physical custody of a grandchild after their slander campaign against you has won them powerful allies. Many times the N grandparent has a lot of extra cash to throw around since they are done raising a family. They may successfully exploit the natural selfishness of the child by using cash or toys to lure them. I have read heart-breaking stories of these kinds of situations often enough that I recognize the clear danger any narcissist grandparent represents. They can even steal your children's hearts from you when the children near adulthood with promises of money, houses, cars, college tuition, etc. as bait.
It is imperative to let yourself know that, without profound evidence to the contrary, your narcissist parent is a narcissist still. You must let yourself know for a fact that your N parent can not be trusted with your most precious responsibility, your children. If you allow contact between your children and your N parent it must never be out of sight. Never for a moment leave your child alone with this serial abuser. They only need a few moments of alone time to inflict damage. A whisper, an insinuation, a pinch, a look. If you consider yourself a responsible parent you will never, ever leave your child alone with your N parent. Ever.
So you've made the decision that cutting off contact with your N parent is a necessity and now you're dealing with questions from your children, or you're anticipating questions. First of all, let us establish another fact. You are the parent. You get to make these decisions without apology or excessive justification. You can assure your child that you are making a wise and loving decision for them as well as yourself. I am not going to script what you should say because you are the only one who knows your children, but you must convey that this isn't up for negotiation. This is not a decision that the child gets to make. Yes, children usually love their grandparents. Children are often quite indiscriminate in their love which is why they need parents to guide them. Not every person is safe to have around and this is a good time to teach that important life lesson. The more matter-of-fact you are, the more matter-of-fact your children will be. When we act hysterical, they will usually reflect our hysteria. If you act anxious, they will act anxious. If you appear unsure, they will push. Model the reaction and attitude you want your children to adopt.
If you have another set of grandparents in the picture then focus on them. It is rare that both sets of grandparents are nasty. Emphasize to your children how much we enjoy being around grandma and grandpa so-and-so (the decent and loving grandparents). Cultivate your children's relationship with the decent, loving grandparents. Teach your children to be grateful for the decent, loving grandparents. Gratitude is a highly effective antidote to loss. Focus them on what they have, not what they don't have. Model that attitude of gratitude.
You will find that the children will eventually stop mentioning the loss of the narcissist grandparent if you are not bringing it up. If you are talking about your Nparent in the hearing of your children then you are inviting them to keep talking about it, too. I can not over-emphasize the need for your explanation to a younger child to be calm, pragmatic, measured and short. Long explanations make you look defensive which will tend to peak the interest of the child and prompt him to push the issue. You can gauge what is appropriate information depending on the age of the child. If the child is older and has experienced or witnessed the Ngrandparent's nastiness in action then you can say more.
Young children are not known for their long attention spans. This works in your favour. With younger children you have the advantage of distraction. It is easy enough to get the child's mind off onto another track. Every parent has done the distraction routine at one time or another. "Mommy, I want to see NastyGran today!" "Honey, we aren't going to see NastyGran today because we get to go to the park and eat ice cream." (Make up fun time on the spot if necessary for this distraction.) "Yay!!" says the kid and off we go. Subject changed, kid distracted. In time, NastyGran will fade from memory. Any bonding that may have occurred will dissipate in the process of time.
Remember, you are the parent. You're older and therefore more experienced which is the point of being the parent. The child is dependent on your good sense and protective wisdom. You're smarter than your child; use that to your advantage (such as using the distraction method). You are the final authority. This is not a negotiable issue. Kidlet doesn't get to decide on this one because they lack the understanding, wisdom, experience and good sense that, hopefully, you have. So don't look like you're unsure or open to quibble. You'll undermine yourself if you look anything but firm and resolved on it. Use your advantages as parent to smooth the effects of the cut-off. Over time this will all quiet down. Kids tend to accept what is. It will happen more quickly if you follow the above advice.
Most of all, do not operate from a fearful mindset. Don't be afraid of your children's possible, or actual, reactions. Don't be afraid that you are depriving them of something important by cutting off a set of grandparents. You are only "depriving" them of bad things. Reassure yourself with that truth. Family is not everything. Blood is not binding. You are escaping the Mob Family. What should connect us is how we treat each other with love and respect. This is always a good lesson to teach our little ones. If any part of you is unsure of your decision then, for Pete's sake, don't show it. Your resoluteness will go a long way toward reassuring your children that you are acting in everyone's best interest. If your children know that you love them, they are going to feel reassured that this decision is also based in your love for them. They will find an added sense of security to know that you, as their parent, are willing to protect them even at the cost of your relationship with your own parent(s). Rather than being fearful, see the plentiful opportunities in this. You are protecting your children from someone whom you've experienced as being abusive; you are reassuring your children that you are in charge and are watchful for their best interests (creates deep sense of security); you can teach healthy family values which include that family doesn't get a pass for abusive behaviour; you can strengthen and reinforce the healthy relationships in your extended family. Kids are less likely to feel like there is a void in their life if you fill it with good things.
Cutting off from your narcissist parent is a good thing. No need to act otherwise. Your children will sense it is a good thing by how you behave. Model how you want them to respond and it is likely they will imitate. Don't be afraid of their questions. Kids are amazingly resilient and well-equipped to handle truth. Parents are supposed to protect their progeny. If your child doesn't agree with how you go about that don't worry. They will often disagree with your decisions for their best interests. Nothing new there. It is your job as parent to make the tough decisions. If you know it is the right decision then proceed with confidence. Showing confidence is a quality of leadership. As a parent you are supposed to be a leader. Lead...and they will likely follow.