Creating name beside expand box for grouped data

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Hi There. I have data that has been recorded every minute for several days. I have created a Group for each day that includes all the rows for that certain day. I am able to expand or collapse the rows (show or hide) so that I am only viewing certain days. I do this by pressing the plus/minus button that appears to the left of the row number when you create a group. My question is, is there a way to have a label display next to that expand/collapse button? I know that I can create a new column that just contains the date (no time) and then filter based on the date, but I am still curious if the other way is possible.
Thanks!