[TOMT] [TV/Series] [2020+] Young girl with terminal illness takes her own life, mother blamed for assisting with her death.

I'm looking for a British based limited series drama that follows an investigation (and potentially court case?) following the death of a young girl/teenager who takes her own life.

The parents are divorced, and the mother is initially accused of assisting in her daughters suicide, as its discovered through investigation that the drug administered could have been done so by the daughter herself.

The daughter leaves a video recording stating the reasons/willingness to die, and it is not suggested at any point that the mother ‘killed’ the daughter, simply that she assisted in her suicide.

During the investigation/court proceedings, the girls younger brother is interviewed and it starts to become clear that in fact the brother has likely assisted in the suicide and has knowledge of the video, and been told what to say by his sister.

I think the mother had realised the brother was to blame, and thus was going along with taking the blame given it would save her son.