Are allied to is a phrase that implies a close relationship or connection between two or more entities. There are numerous synonyms that can be used in place of this phrase, including "are connected to," "are affiliated with," "are associated with," "are linked to," and "are related to." These synonyms suggest different degrees of closeness in the relationship, such as "connected to" implying a more casual or indirect link, while "affiliated with" implies a more formal or official association. Regardless of the specific word chosen, using synonyms for "are allied to" can add variety to your writing and better convey the nature of the relationship.