This work develops a dynamic analysis of presupposition projection based on similarity relations between local and global contexts, drawing on accounts of counterfactual conditionals (Lewis 1973, Stalnaker 1978). The proposal addresses issues with presuppositions triggered in counterfactual contexts, where existing local-context based accounts (Heim 1983, 1992, Schlenker 2009) make faulty predictions when considering counterfactual contexts that are logically distinct from the global context. This work addresses this issue, deriving projection by requiring the global context to be similar to the local context. It also addresses the triggering problem by treating presuppositions as entailments (Abrusán 2011) and deriving projection by calculating similarity over partitions of the context set determined by the question under discussion (Simons et al. 2017). The analysis is implemented in a propositional version of CDRT, using propositional variables to model local and global context sets (Brasoveanu 2006, AnderBois et al. 2015, Hofmann 2022, 2025).