The investigation of Human-Robot Interaction in digital ecologies going beyond the dyadic one-to-one interaction is a topic with increasing relevance. Yet the characteristics of this field are vastly unexplored. To map out the field of human-robot interaction going beyond one-to-one, and thereby guide future research, we performed a thorough literature review containing all 142 publications (2006-2019) from the HRI Conference investigating interaction beyond the dyadic form. Our analysis approach is inspired by the terminology used in the human-computer interaction field of digital ecology interaction. Our main contribution is a comprehensive literature review of all full papers published at the HRI Conference as well as the classification of research going beyond one-to-one. Further, we identify an attention shift towards an increased focus of digital ecologies, corresponding to around 40% in 2019, as well as a focus on the type of digital ecologies, which is primarily related to topics related to one-to-many interaction. Lastly, we discuss several potential future topics of interest for research going beyond one-to-one.