There are many synonyms for the phrase "are one family," each with its unique connotations and implications. One option could be "are united," which emphasizes the strength and solidarity of a group that works together towards a common goal. Another synonym could be "share a bond," bringing attention to the personal and emotional connections that bind people together. "Belong together" highlights the sense of inclusion and acceptance that comes with being part of a family, while "connected" implies a more tangible and practical link between individuals. Ultimately, the choice of synonym depends on the context and desired tone, but each one reinforces the idea of a supportive and loyal community.