The purpose of this article is to introduce eTransition models, modelling enterprise architectures during their transition from traditional to digital, in the context of collaborating enterprises, which are designing, manufacturing and, in a true multi-lifecycle fashion, even de-manufacturing products. Our approach is analytical, quantitative and open-source computational, following object/componentoriented, validated enterprise (i.e. collaborative digital factory) modelling methods, models and software tools, as well as a system architecture written in the Unified Modelling Language. This approach enables us to analyse individual, as well as eCommerce-linked, B2B (business to business) collaborative enterprises, in particular to analyse their eTransition processes, and then design all critical aspects of their design, manufacturing and logistics processes over the web, manage their manufacturing lines and provide electronic support systems for operators. In our research, we have used the Rational Rose Unified Modelling Language (UML, an industry-standard, object-oriented software and system analysis/design and documentation method), as a language for specifying, constructing, visualizing, and documenting the artefacts of such a software-intensive system, Ranky‘s CIMpgr (CIM process, generic, resource) object-oriented process modelling method, and we have targeted the modelling efforts to describe concurrent, distributed systems, such as the electro-mechanical manufacturing and de-manufacturing systems we have studied at our collaborating industrial partners‘ sites.