Within mobile mixed reality experiences, we would like to engage the user's s head and hands for interaction. However, this requires the use of multiple tracking systems. These must be aligned, both as part of initial system setup and to counteract inter-tracking system drift that can accumulate over time. Traditional approaches to alignment use obtrusive procedures that introduce explicit constraints between the different tracking systems. These can be highly disruptive for the user's s experience. In this paper, we propose another type of information which can be exploited to effect alignment: the behaviour of the user. The crucial insight is that user behaviours such as selection through pointing introduce implicit constraints between tracking systems. These constraints can be used as the user continually interacts with the system to infer alignment without the need for disruptive procedures. We call this concept behaviour aware sensor fusion. We introduce two different interaction techniques the redirected pointing technique and the yaw fix technique to illustrate this concept. Pilot experiments show that behaviour aware sensor fusion can increase ease of use and speed of interaction in exemplar mixed-reality interaction tasks.