Neighbours have covid19 and it makes no sense

They have 4 kids, 14, 12, 9 and 1 yo. The 9yo child tested positive on nov 5, and so did the mum but everyone else was negative so they rang NHS covid for advice and were told they both had to isolate and everyone in the house needs a PCR test.

They did PCR test and the 12 yo also got positive. So mum 12 and 9 all have to isolate, Dad can still go to work and the 14 can still go to school.

Yesterday 9 got a negative result and was allowed back to school, mum and 12 still positive so have to isolate another 10 days. So dad is going to work, 14 and 9 are at school and mum 12 and 1 have to stay home. But mum is now worried that dad 14 and 9 could be spreading it by going to work n school.

9 wants to play out with my daughter (they are in the same year and always play together). I don’t know what to do? Mainly coz its ok for her to be sat in a classroom all day with other kids but i also know how poorly her mum n brother are.

So confused 😕