Hi welcome to the site :) this sample chapter may help
http://www.pearsonschoolsandfecolleg...orceunit35.pdf
Strategies could include making sure everyone knows each others names - badges for children and staff.
Helping children to communicate with each other - group games, activities, contributing ideas, resolving conflict, respecting disagreement, valuing the diversity of each child's culture, their interests, skills and abilities.
Page 90+ of the Playworker handbook looks at building relationships
Best wishes xx