Some business processes in medical diagnostics involve many large-scale systems distributed through the Roche enterprise and customer clinical laboratories. The systems fulfill valid purposes, can operate separately, and are managed for their own purpose rather than the purposes of the whole. Allocating business functions to specific system components and defining interfaces present significant challenges for architecting such large and complex IT and software system-of-systems (SoS). It requires supporting decision criteria with data and accommodating fast evolution of the architecture. For architecting SoS in Roche's product context, we defined a customized method based on the U.S. Department of Defense Architecture Framework. The method has six steps, with start/finish criteria and deliverables for each. In this talk, I will illustrate the steps using examples from Roche. The method can be applied in Agile projects if the sprints are oriented on implementation of workflow. The customized method for architecting SoS at Roche was applied to business processes related to Remote Solutions and the Internet of Things. It facilitated quick definition of models, derived data to support decision making and allocation of business functions and resources to existing and to-be-developed systems, and identification of common resources and interfaces for their exchange.