The range of technology users is continuously increasing from adults to children as well as seniors. This introduces new age-related requirements and considerations. Modelling frameworks are used to assist the software development independently of the platform and the coding technology. However, very limited research has been done on age-related issues within the modelling and design frameworks. In this paper, we investigate how human-centric aspects regarding age can be better modelled by extending wire-frames. We collected both developers and end-users feedback through questionnaires and introduced an extension of wire-frames to cater for decisions regarding age within the modelling framework. We then conducted a usability testing by using the extended age-modelling wire-frame approach to design a news app. This shows that when using our extended wire-frames, developers can cater for different user types and their accessibility needs easily. We finally conducted cognitive walk-throughs with three personas, representing children, adults and seniors to evaluate the prototype app. The results proved the usability of the app for all age groups.