Do we still need to respond to a DSAR given that after redacting information about other individuals, the report is rendered nonsensical?

The client has received a subject access request (SAR) from the parent of a child (under 10) seeking access to the child's social work record. The client has indicated that the record refers to third parties (family members). By redacting the references to these third parties, the record would be rendered nonsensical.

If this is the case, does my client still have to disclose the record to the parent, or is it entitled to not disclose on the basis the record is rendered nonsensical by virtue of the redactions?

I understand that under the Freedom of Information Act 2000 if redactions are so widespread so as to remove the meaning from a page in a document that page does not have to be disclosed. Does the same principle apply to SARs?