Topic: IAutoComplete2 To show and interpose different values

Whether probably to implement by means of IAutoComplete2 such piece: we Show in the help in the list of autocompletion of a line of type "Subst1 Subst2", and after a choice of a line - it is interposed into a text box a line only Subst1. And thus it is necessary to catch somehow the moment of a choice the user of a line from the list and to learn Subst2, to interpose into other field. Prompt, whether it is possible?