Table 1 Phases, data collection, methods and themes

Phase	Data collection methods and themes
1. Environmental Scan	Interviews with nursing home manager (n = 1) Key themes: Current practice; Impressions of the proposed COVID; ACP intervention; Potential barriers and facilitators towards implementation. Nursing home profile questionnaire (administered as part of interview with nursing home manager) Key themes: Resident and facility profile (including COVID outbreaks); Care home policies and procedures; Staff profile; Staff training; Use of technology; Contact with health and social care professionals; Response to COVID-19. Interviews with nursing homes staff (n = up to 4 registered nurses who undertake training) Key themes: Demographics; Current practice; Experience (including confidence & concerns about completing ACP in the context of COVID-19); Communication & technology; The role of family members; Impressions of the COVID-19 online training; Potential barriers & facilitators. Interviews with family carers (up to n = 6) Key themes: Background information/Demographics; Use of technology and current communication approach with nursing home/relative; Information needs
3. Follow up data collection Completed 1–2 weeks following delivery of the online training by participants recruited during the environmental scan	Interviews with nursing home managers, staff, family carers & the external facilitator (n = see above) Key themes. Family carers: Satisfaction; Acceptability; Impact on attitudes; knowledge & behaviour; Technology & communication. Nursing home manager/staff: Satisfaction; Acceptability; Impact on attitudes, knowledge & behaviour; Communication & technology; Implementation. External facilitator: Satisfaction; Acceptability; Training & sustainability. Feedback questionnaires (including website user experience, preparedness, communication)