Grandma or not

Just be happy your GC has so many people who love her. I really would just accept it, as to try and change it may cause friction. Don’t concern yourself with this new lady. It is up to your SIL’s family to sort her, if anyone is going to. Just be the source of good reason and common sense when you’re needed.

I agree with others, let the family sort this one out. You have your special place Newatthis so don't let resentful feelings spoil things. Using the lady's forename as in "Nannablank" would be a good compromise.

I would think it's up to your grandchild's parents to say if they are unhappy about the new woman referring to herself as nanna.

I wouldn't allow it, personally, but everyone is different.

I quite understand how you feel, but you will always have a special place in the family as the original grandma.
The step grandma hopefully will be an extra kind person that your grandson can spend time with. The issue of whether or not she is a “gold digger” is not really yours to worry about.

My grandson has five 'grannies' due to divorce and remarriage in his dad's family. I don't mind at all - as I know I'm his favourite!

DH felt a bit the same when other nan had a new man in her life who became another grandpa. The other man has long gone now and is not mentioned. At the end of the day all that matters is that you are your grandson’s grandma. Let your grandsons parents sort it out if they think it’s a problem. Otherwise let it go.

My DGD has a stepfather, and a stepmother (never referred to as that), both called by their first names. The stepparents' parents automatically opted to be called by their first names. Neither set seems to have wanted to usurp the position of grandparents.

Nevertheless, our DiL's parents - and their family - treat DGD as family.

Maybe your SiL should just refer to his father's lady friend by her first name, regardless of what she calls herself, so that your GC has a clearer understanding of the situation. In all other respects there's probably not a lot he can do about his father's relationship.

Not much you can do unless you feel able to talk to your SIL but I assume he knows about this. What does he think and does he want to get involved by mentioning it to his father? You can't do anything yourself as you are too far removed and not close to these people. I think you'll just have to put up with it and work on having a close, loving relationship with your GC. You don't mention your GC's age but I'm sure this won't affect his/her relationship with you long term especially if the intruder exits the scene.

Newatthis We none of us have any rights over our DGC, I am sorry to say, and I am very glad that I know and like all my other co-GP.

It will feel like a shock but if she makes him happy, isn't that more important than any loyalty to the deceased?

Your relationship with your DGC is not going to change much but if you feel bitter and angry , those feelings may project themselves.
It may never come to anything...

It really annoys me ....really !!! These women enter into families and take on the title of 'grandma'. My Ex's new wife is called Nana by 4 of my 6 grandchildren. But my daughter's children call her by her first name. They are teenagers and the others are toddlers, so in a way, I can understand.