Although Software Product Lines are recurrently praised as an efficient paradigm for systematic reuse, practical adoption remains challenging. For bottom-up Software Product Line adoption, where a set of artefact variants already exists, practitioners lack end-to-end support for chaining (1) feature identification, (2) feature location, (3) feature constraints discovery, as well as (4) reengineering approaches. This challenge can be overcome if there exists a set of principles for building a framework to integrate various algorithms and to support different artefact types. In this paper, we propose the principles of such a framework and we provide insights on how it can be extended with adapters, algorithms and visualisations enabling their use in different scenarios. We describe its realization in BUT4Reuse (Bottom--Up Technologies for Reuse) and we assess its generic and extensible properties by implementing a variety of extensions. We further empirically assess the complexity of integration by reproducing case studies from the literature. Finally, we present an experiment where users realize a bottom-up Software Product Line adoption building on the case study of Eclipse variants.