This paper illustrates the use of ?feature matrices?, a technique for handling ambiguity and feature indeterminacy in feature structure grammars using unification as the single mechanism for processing. Both phenomena involve forms that can be mapped onto multiple, often conflicting values. This paper illustrates their respective challenges through German case agreement, which has become the litmus test for demonstrating how well a grammar formalism deals with multifunctionality. After reviewing two traditional solutions, the paper demonstrates how complex grammatical categories can be represented as feature matrices instead of single-valued features. Feature matrices allow a free flow of constraints on possible feature-values coming from any part of an utterance, and they postpone commitment to any particular value until sufficient constraints have been identified. All examples in this paper are operationalized in Fluid Construction Grammar, but the design principle can be extended to other unification-grammars as well.