 Lin and Kelly (2012) propose that qualitative belief update ought to  track partial belief update. On their picture, partial and full beliefs are maintained and updated by parallel cognitive systems. The first system, governed by the probabilistic norms of Bayesian coherence and conditioning, is precise, slow and cognitively expensive. That system is engaged for important deliberations requiring a lot of precision and occuring without much time pressure, e.g. retirement planning. The second, which in some way maintains and updates full beliefs, is quicker and less cognitively burdensome. That system is engaged in ordinary planning: grocery shopping, or selecting a restaurant for a department event. (For an objection to the two systems view, see Staffel (2018).) What keeps these two parallel systems in sync with each other?