How to fix text message threads merging with unintended recipients on iPhone?

Recently when I send my daughter a text message it also goes to two of her friends. They are in her contacts, they are not in my contacts. I have never sent them messages ever and have never had their numbers.

On my phone it shows that I only sent in to her. On her phone it shows the other two as well.

When she replies to my text message, it starts as new thread on my phone with me and the three of them.

The reverse happens when she sends me an individual text.

Her two friends report that they do get these text messages.

It has gotten to the point that I can’t text her directly because they will get it, so I text her in a thread with her brother.

We do have her in a family group, but it isn’t happening with anyone else.

We are stumped.

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