You may be able to cover or insure your adult child's possessions under your contents policy. If your adult child lives with you, their possessions can be covered under your contents policy - you'll just need to make sure your sum insured amount is enough to cover all of your family's belongings. To check whether specific items are covered, look in your policy document under the section 'What you are covered for'.
If you're wanting to insure your adult child's belongings outside of what's described above, or have any questions, please contact us.