This article aims to reflect on the main constraints encountered in recovering music-theatre works that involve a variety of diverse aspects that are relevant to their performance. As well as the score, scripts or other additional documents, the works considered here also include electroacoustics recorded on magnetic tape, consequently requiring specific approaches in order to preserve such kinds of works. Video recordings of concerts are important for understanding, documenting and eventually restaging these works. This idea is not new; audio-video recordings have for many years served as sources for documenting live performances (music-theatre or art performances). However, it is still important to discuss just how and with which tools these very important documents might be preserved and exploited. Hence, the study of the structure of Molly Bloom and FE...DE...RI...CO…, both with music by Constança Capdeville, enables an understanding of the processes in which documentation is relevant to preserving such a valuable cultural heritage.