The field of research dedicated to Accessible Digital Musical Instruments (ADMIs) is growingand there is an increased interest in how different accessible music technologies can beused to promote diversity and inclusion in music-making. Researchers currently voice theneed to move away from a techno-centric view of musical expression and to focus more onthe sociocultural contexts in which ADMIs are used. In this study, we explore how “Funki”, aset of ADMIs developed for students with Profound and Multiple Learning Disabilities(PMLD) can be used in a collaborative music-making setting in a Special Educational Needs(SEN) school, together with assistants. Previous findings have suggested that the musicalinteractions taking place, as well as the group dynamics, were highly dependent on thesession assistants and their level of participation. It is therefore important to consider theactive role of assistants, who may have little or no prior music training. The instrumentsprovided should allow the assistant to not only help the students in making music but alsoenable the assistants themselves to create sounds without interfering or disturbing thesounds produced by the students. In the current work, we show how the Funki instrumentscould be expanded with WebAudioXML (waxml) for mapping user interactions to controlmusic and audio parameters and make it possible for assistants to control musical aspectslike the tonality, rhythmic density, or structure of the composition. The system was tested in acase study with four students and their assistants at a SEN school, including semi-structuredinterviews on how Funki supported inclusive music-making and the assistant’s role in thiscontext. The findings of this work highlight how ADMIs could be conceptualized anddesigned to include special education teachers, teaching assistants, and other carers moreactively in collaborative music-making.