In case of polite plural subject, … more verb-like predicates tend to agree with features of the surface subject, while more noun-like predicates tend to agree with the underlying subject.
Standardized
Whenever predicates agree with subjects in number and there is a politeness contrast for pronouns of address, with plural forms serving as polite singulars, the more verb-like a predicate the likelier it is to agree according to surface features of the subject (i.e., to be plural), and the more noun-like a predicate the likelier it is to agree according to the referential semantics of the subject (i.e., to be singular).
Keywords
agreement, number, politeness
Domain
inflection, syntax, semantics
Type
unconditional
Status
achronic
Quality
statistical
Basis
Slavic, Romance languages, Modern Greek (all Indo-European)
See #429, where the Standardized version is implicational.