Hierarchy for a column Users?

I am looking for an advice to the following issue working in a report like the one below.

My table contain a column Users (type text). Those users belong to two main groups and perform many movement in the ERP.

So in the Visual level filter I would like to insert two groups instead of select each time all users  =< "98999" and => "99000" selecting one by one.

How can I create two groups and put one of them in the visual level filter?

Thanks