What is the best way to grouping comments in wordpress?

In WordPress, I want to group comments by a numeric value to use each of the groups in a special parts that I want. Any of my groups have a numeric value as identifier. For example, I want to put comments 1,2,3,4,5 in group 1 and comments 6,7,8,9,10 in group 2. So the group number of comment 7 is 2 and comment 4 is 1 and etc.

I use comment_karma field that exists in WordPress comments table to save the group number of each comment in the row of it. But I am not sure to use comment_karma field or create a new meta field in commentmeta table for each comment to hold comment group in meta value instead of the comment_karma field. What the way better to use?

By use meta field I need to join tables to get results and it some difficult. But maybe it better! Because comment_karma field maybe alter or change with plugins or other projects that certainly damage to my information.

Other idea is that I add new column to WordPress comments table with custom name. How about this way? Is it good?

Summary: there is some way to group the comments. Grouping them with comment_karma field or add custom column to comments table or use meta field in commentmeta table. What is the best way? Thanks.