LFT - data protection breach?!

[polyjuicepotion]

Please help, I need urgent advice.
My DC has invited a friend over. They are both secondary school age. I know there have been some children who were self isolating in the class meaning that covid has been going around at school.
My DC forgot to do their LFT today (usually done twice weekly) so I suggested they do it after school, and since the friend said they forgot to do theirs as well I asked if they wanted to do it too.

Long story short, both tests negative but later on I received a furious text from the friend's mum who accused me of breaching data protection and said that she will take legal action for making her child do the test at my house.
Any advice appreciated.

What I take from this thread and from a similar one about a school test, is that there is a surprising number of parents out there who haven't brought up their DC to say to the present adult that they don't wish to do something, eg a LFT. Or is it that the DC is quite happy to do the test but knows the parent won't like it so adjusts the report?

I was admonished years ago by a 7-year-old for offering frozen peas, "we only eat fresh". So I'm not impressed with these secondary aged DC who apparently don't have the skills or confidence to politely turn down something offered.