The phrase "is of family" can be better expressed by using synonyms such as "belongs to the family", "is a member of the family", "has familial ties", or "is kin to the family." These synonyms convey the same meaning and help to add variety and depth to your writing. Other possibilities include "is related to the family", "shares a lineage with the family", or "comes from the same bloodline." Depending on your intended context, selecting the right synonym for "is of family" can enhance your writing and make it more engaging for your audience.