How to make two columns of a table requiring to be unique at user request

I have tried validating the user request like this:

$data = $request->validate([
            'fname' => 'nullable',
            'lname' => 'nullable',
            'gender' => 'required',
            'mobile' => 'required|unique:users,usr_name',
            'ncode' => 'nullable',
            'password' => 'required',
            'password_confirmation' => 'required',
        ]);

So as you can see I have said that the mobile filed value must be unique:users,usr_name but I do need to check that it is unique at members table as well (the mbr_mobile column):

unique:members,mbr_mobile

So how to combine these two rules at once?