Daughter’s Birthday

My daughter’s (12) boyfriend’s mother just called me and asked if she could throw her a birthday party at her house. She has 6 kids, they’re a blended family just to put that in perspective. I think they all go to separate parents’ houses for shared custody.
I’m not really sure how to feel about this as my husband and I have done a lot for her birthday. We didn’t throw a party but we took her and her brother to Busch Gardens. We took her out to her favorite restaurant. We usually cater to her for about a week, to make her feel special.

I asked her if she had mentioned to his mom that she didn’t have a party, but she said no. I feel awkward and don’t understand. I didn’t know what to say to her, other than I’ll speak with my husband about it.
She just commented how the kids all love her and she’s very well-behaved and has good manners. I feel like a boundary is being crossed but at the same time I feel like that’s really nice of her. Should I let her do that?
Please help…