Putting brothers fiancé’s kids names on cookie jar for my mother???

Ok I know the title sounds weird so let me explain.

I have three kids.

My brother is engaged to a girl who has two young kids- they are not my brothers kids, therefore not my mothers grandchildren.

Sooooo I ordered my mom for Christmas (I know it’s kind of early) a personalized cookie jar, it says grandmas kitchen. I added my kids names, and also my brothers fiancé’s kids names. I know they aren’t my mother’s grandchildren, but I wasn’t going to leave them out, they are part of the family, and they have been for a while. They are currently 5 and 6 years old and we have known them since they were 2 and 3 years old. It’s not the first time they were added to personalized things, my mom has ornaments with their names on them, and also Christmas stockings with their names on them. But this is a little different because the cookie jar says “grandmas kitchen” - Although my mom has posted on Facebook pictures of my kids with her kids and captioned it “my grandchildren” and she has a picture frame that says my grandchildren with a picture of all the kids

So I didn’t ask my soon to be sil (they are getting married in less than six months if that’s relevant) the thought to ask her never even crossed my mind, I mean, it’s just a cookie jar.

So I showed my friend and she told me it’s wrong to include them without asking my SIL first- she said it’s disrespectful as the kids already have grandparents, and how would the grandparents feel. She also said I crossed a boundary with my SIL, and anytime her children’s names are even mentioned, I need to check with her first, and I am being a SIL who crosses boundaries

I mean- I do agree maybe I should have like ran it by her first, but my SIL is so laid back I can’t imagine her being mad about it. I guess maybe I should have considered the other grandparents, but like it’s literary a freaking cookie jar, it’s not that serious.

I also don’t want to be a sil who crosses boundaries. Like I have a SIL (husbands sister) who is like that and I DONT want to be “that in-law” so if I am crossing any lines, please tell me so I can fix myself to not be that way.

Thank you 😘