Software architecture has been widely used to describe the design of a software system. Its maintenance over time can be costly, especially when maintainers have to recover software architecture knowledge due to poor design documentation. Capturing design decisions is one important aspect in documenting design and even though there has been some work in this area, there has been little emphasis on the evolution of design decisions. In this paper, we analyze design decision models and the issues of not capturing evolving decisions. To tackle these issues, we propose a set of decision attributes that can be used to support evolving decision models.