Table 1 A list of the feasibility measures, its metrics and aggregation, and the time point of measurement

Recruitment rate

% participants of the target for each group are randomised

t0 (allocation)

Retention rate

% participants of those randomised completing at least one post-treatment measure

t8 (1-month post-treatment)

Completion of clinician-reported fidelity measure

% therapy sessions in each intervention where the dose tallies were was recorded

t1 to t6 (therapy)

Therapy protocol adherence

% therapy sessions in each intervention where the minimal dose was achieved

t1 to t6 (therapy)

Perceptual rating of treatment wordlists

% rated sessions

t(−1) and t1 to t8 (baseline, therapy, and post-treatment assessments)

Patient-reported outcome measure Cleft-Q (functioning and distress subscales)

% completed questionnaires for each intervention arm

t(−1), t7, t8 (baseline and both post-treatment assessments)

Patient-reported outcome measure ICS

% completed questionnaires for each intervention arm

t(−1), t7, t8 (baseline and both post-treatment assessments)

Patient-reported experience measure

% completed questionnaires for each intervention arm

t8 (1-month post-treatment)

Intervention acceptability questionnaire

% completed questionnaires for each intervention arm

t8 (1-month post-treatment)