It is DN's birthday tomorrow, I have organised her party.
It's going to be quite big, 25 kids have RSVPed, plus there will be family.
SIL (my other brothers wife, not DN's parents) has just texted me with "Its ok if I bring my friend from work tomorrow isn't it. She is really good with kids and she is staying with us this weekend so I said she could come to the party"
I have never met or heard of this person before, but I feel as if it would be UR to say no.
The thing is I was with SIL last night and she never mentioned this friend visiting.
So WIBU to say actually SIL no it isn't ok to bring some random stranger to our neices birthday party.