The metadiscourse used in institutional dialogue is envisaged in this investigation as a set of discursively and rhetorically structured utterances meant to contextualise, as well as overstate or understate the interlocutors' statements with respect to the degree of involvement, topical explicitness, positioning, interpersonal rapport and audience appeal. The main goal is to analyse the interplay between shifting metadiscursive strategies and ritualised discursive practices by examining instances of parliamentary interaction that shape participant role shifts, private-public communicative interfaces, and multiple audience targeting strategies. A rhetorically significant category of metadiscursive strategies used to surreptitiously introduce controversial comments are the rhetorical parentheticals. In terms of their position and role in the discourse, two main types of metadiscursive parentheticals have been identified in institutional dialogic interaction: parentheticals that function as inserted metadiscourse (occurring either by juxtaposition, before, after or between whole discursive units) and parentheticals that function as embedded metadiscourse (occurring between two constituents of one specific discursive unit). A pragma-rhetorical approach has been adopted for the analysis of various types of metadiscursively functioning parentheticals in order to identify shifts and overlaps between the personal and interpersonal levels and to examine multi-level correlations between the interlocutors' articulations of complementary or competing representations and interpretations. Context-specific examples illustrate how interlocutors use parentheticals to adjust their discourse to shifting rhetorical situations, vary the effects of their rhetorical appeals by addressing interchangeably or simultaneously several audiences and choose to reinforce/cancel previous assumptions referentially, relationally and/or evaluatively.