Mismatches in free relatives – grafting nanosyntactic trees

German free relative constructions allow for case requirement mismatches under two types of circumstances. The first is when the case required in the embedded clause is more complex (NOM < ACC < GEN < DAT) than the case required in the main clause, and the relative pronoun takes the form of the embedded clause case. The second type of circumstance is when the form that corresponds to the two required cases is syncretic. I propose an analysis that combines Caha’s (2009) case hierarchy in Nanosyntax with Van Riemsdijk’s (2006a) concept of Grafting. By placing case features as separate heads in the syntax, a less complex case can be Grafted into a different clause, explaining the first type of circumstance. The second type makes reference to the fact that syncretic forms are inserted via the same lexical entry (Superset Principle). A cross-linguistic comparison shows that it is language-specific whether a more complex case requirement in the main or embedded clause causes non-matching non-syncretic free relatives to be grammatical. For all languages it holds that the relative pronoun appears in the most complex case required, which provides additional evidence for case being complex and more complex cases being able to license less complex cases