Receiving liability notes from collection agency

My child has not dwelled with me for two years, but still values my address for correspondence. I have opened notes in her title pertaining to some liabilities amounting to apprx £9000. I hold posting the notes back to mailer, asserting "no longer at this address" I would like to understand if, if it arrives to "Baliff" stage, if they can grab my items, as there is not anything in my dwelling that pertains to him. Is liability is associated to me furthermore as i am his father? If my child will not yield liability then who will be to blame for his debt? How can i eliminate my address from the record? Can I contact National Asset Management for my help!