Multi value parameter select all help needed

Hi, I have a requirement where i have a multivalue parameter, Is there a way if my user doesnt select one or all values the report will bring back all records ?

I understand the multi value parameter will let user input more than one value by opting to select all, is there another way without selecting all the report should bring back all available records irrespective of the MV parameter?

Please direct me to a solution.

Thanks