This study explores the nomological network of family‐supportive supervisor behaviours (FSSBs) at the weekly level. Drawing on the tenets of the work–home resources (W‐HR) model and the conservation of resources theory, we integrate relational resources in the model and investigate their role as triggers of FSSBs. Furthermore, we explore how FSSBs relate to both within domain (production deviance and employee creativity) and between domain (sleep quality and dyadic adjustment) employee outcomes, with a focus on exhaustion as a mediator. Our findings show that (1) spousal support experienced by the supervisor is positively related to the employee's perception of FSSBs as enacted by the supervisor, (2) employees' perceptions of FSSBs are negatively related to employees' production deviance and (3) exhaustion is a mediator between FSSBs and employee outcomes of creativity, sleep quality and dyadic adjustment. Our findings across two multisource and diary studies underline the importance of designing and implementing FSSBs in a dynamic fashion.