For simulations involving complex objects, a number of different properties must be represented. An example of this is in modeling an object undergoing combustion—heat amounts, fuel consumption, and even object shape must be modeled and changed over time. Ideally we would put everything into a unified representation, but this is sometimes not possible/feasible due to measurement limitations or the suitability of a specific representation. In this paper we define a multi-representation framework for dealing with multiple properties and their interactions within an object. This model is especially useful in physically based modeling, where the time variation of some properties affect other properties including geometry or topology. As a motivating example case, we present a method for modeling decomposition of a burning object. CR Categories: I.3.5 [Computer Graphics]: Physically Based Modeling