Most deaf children are born to hearing families. During the last twenty years deaf children, in increasing numbers and at an early age, receive a cochlear implant, a highly technological hearing device. The aim of this qualitative, longitudinal, single-case study was to explore and describe critical changes in naturalistic, video-observed interactions between Deaf family members. In this study, Diana, a congenitally deaf girl, acquired Swedish Sign Language (SSL) from birth and received a unilateral cochlear implant (CI) at the age of thirty-five months. Diana eventually developed spoken Swedish as a second language. The study is triangulated with information from the CI-team records spanning the ages thirty-one months to eight years. The latter age relates to the time when Diana's receptive skill of the vocal mode was assessed to be seven years and eleven months. Guiding or mediating parameters include the parents' positive attitude towards meaning-making interactions and encouragement of the child's own bimodal activity. Diana's hearing twin brother's challenging of her vocal modality and Diana's simultaneous bimodal production (SSL/spoken word) seemed to self-scaffold her second language acquisition. Further, her bimodality also assisted her family's understanding of her utterances; in addition the other participants' way of using bimodal interchanges scaffolded her perception. The continued education in sign language seemed to be an asset as Diana could continue her social and intellectual development at the same time as she was acquiring a second language. Reported aspects of mediated communicative actions might also influence a broader field of special needs.