This paper is derived in a larger study funded by the charity Catch22, which involved extensive focus groups and interviews conducted with 42 children and young people aged 10-22 years, during the COVID-19 lockdowns in the United Kingdom. A large number of the children and young people involved had experience of the criminal justice system, the care system and alternative education programmes. The study explored their experiences of online platforms, social media platforms, apps and gaming; experiences of online harms and the impact this had on their lives; perceptions of what ‘acceptable use’ is in online spaces; views on law enforcement’s role in addressing online harms and what future regulatory frameworks and arrangements should be developed. Further, the study included 15 qualitative semi-structured interviews with key stakeholders and professionals from police, safeguarding, youth work, victim service provision, tech and gaming companies, regulators and wider industry. It also involved collection and analysis of quantitative data from service providers pre-pandemic and during the UK lockdowns. This paper will explore the significance of sibling support. It will draw on the theory of ‘siblingship’ as developed by Goetting (1986). Young people described assisting younger siblings who experienced ‘unwanted content’ and ‘unwanted contact’. More broadly in relation to online safety, Third et al. (2013: viii) noted that older siblings can play a key role in ‘supporting the safe online engagement of younger users’. This paper also explores how young people refer to challenges and issues for younger children in online spaces, utilising them as an example of why better protections should be put in place.