In family treatment, building and evaluating multiple alliances with family members is complex. We investigated the occurrence and development of discrepancies between therapists' alliances with different family members, and therapists’ evaluation of these multiple alliances and discrepancies. Participants were 92 parents and 61 children and adolescents from 61 families receiving home‐based family treatment. Family members, therapists, and observers reported early and mid‐treatment alliance. We found significant discrepancies, with strongest alliances with mothers, followed by fathers, and then youths. Differences became smaller during treatment. Therapist‐reports yielded similar discrepancies as compared to client self‐reports and observer‐reports. At T1, the correlation between therapist‐ and client self‐reports was moderate and significant for alliances with mothers, but insignificant for alliances with fathers and youths. At T2, these correlations were large for alliances with mothers and fathers, but not for youths. Our findings demonstrate that therapists have stronger alliances and are more congruent in their alliance perspective with parents (especially mothers) versus youths.
