Capital Gains Tax - Discretionary Trust – disabled beneficiary

I am a surviving Trustee of a Discretionary Trust created under the Wills of my parents. Trust assets include my parents’ former home and possible beneficiaries included my younger brother, who had mental health problems and lived with my parents. By agreement with the then Trustees, he continued to live on his own in the house. He died on 17 August 2021, and sale of the house was completed on 31 July 2023. It appears that as Trustee, I can claim Private Residence Relief in assessing any Capital Gains Tax liability arising from the sale of the property, to be based on any increase in value from 9 months after my brother’s death i.e from 17 May 2022 However, it seems possible that final period exemption: disposals by disabled persons rules may apply, giving a 36 months final period of ownership, as I believe my brother qualified as a Disabled person He had been “sectioned”– compulsory detention under the Mental Health Act - at least twice, in 1980 and in 1992 He had been under the care of an NHS psychiatrist and had free medication, possibly Lithium, administered by his GP every month. He was in receipt of an indefinite Attendance Allowance at the higher rate for help with personal care He was supported by monthly visits from Community Mental Health Practitioners which I think was “Section 117 Aftercare” under the Mental Health Act If this is acceptable, no Capital Gains Tax will be payable. I welcome your advice

Hi
The guidance at Disposals by trustees: reliefs advises that private residence relief is available for the disposal by trustees of a dwelling-house which has been the only or main residence of a beneficiary or beneficiaries entitled to occupy it under a settlement may well give rise to a chargeable gain or allowable loss.  
CG64986 goes on to advise that where the dwelling house was that of a disabled person, the relief can be extended to 36 months.  (Private residence relief: final period exemption: disposals by disabled persons etc. from 6 April 2014).