If one person in a household has .......

[Shizzlestix]

been in contact with someone who tested positive, has been told to self isolate for 14 days, shouldn’t the rest of the household also do so? She isn’t showing symptoms. Yes, I am clueless.

Nope. Dd was named as a close contact after one of her class tested positive, she had to isolate for 2 weeks, the rest of our household could go about our business as normal unless she started showing symptoms.

No
Only if that person then gets symptoms

This is the guidance for if you’ve been told to isolate by test and trace.