A useful shorthand in English is placing the “s” in parentheses, such as in phrases like “the girl(s) may come”. This indicates that the phrase may relate to one or multiple individuals or objects.
I have chosen to call this a shorthand since there is no verbal form. If reading the above statement out loud one would have to say “girl or girls” or edit the statement to the correct context.
In Diinlang plurality is indicated by the form of the determiner. A singular object has the articles “ve” or “je” and plural has “vez” or “jez”. The plural forms of the pronouns follow the same convention: “em, yu, ze” become “emz, yuz, zez”.
Clearly “optional plurality” could be indicated by “(z)” but it would be nice to have a form that could be distinguished in spoken conversation. I am not sure of the best way to do this. It may be to add an ending to the plural form that makes it less definite. Or it may be better to create a new determiner, effectively a quantifier that will mean plural or singluar.