Create new dimension using values from another dimension in SQL?

I currently have a SQL table that looks something like this:

   RuleName      | RuleGroup
---------------------------
Backdated task   | DRFHA  
Incorrect Num    | FRCLSR
Incomplete close | CFPBDO
Appeal close     | CFPBDO
Needs letter     | CFPBCRE
Plan ND          | DO
B7IND            | CORE

I am currently writing a stored procedure in SSMS that pulls these dimensions from the existing table. However, I also want the procedure to create a new dimension that will create a "SuperGroup" dimension for each rule based on the text in it's RuleGroup (and an other column for the rest). For example:

   RuleName      | RuleGroup | SuperGroup
--------------------------------------------
Backdated task   | DRFHA     | Other
Incorrect Num    | FRCLSR    | Fore
Incomplete close | CFPBDO    | DefaultOp
Appeal close     | CFPBDO    | DefaultOp
Needs letter     | CFPBCRE   | Core
Plan ND          | DO        | DefaultOp
B7IND            | CORE      | Core

I have currently tried used the "GROUP BY" function, as well as using SELECT with several "LIKE" statements. However, the issue is that this needs to be scaleable - although I only have 21 groups right now, I want to automatically sort if new groups are added.

Here is the SSMS procedure as well:

CREATE PROCEDURE [Rules].[PullRulesSpecifics]
AS
BEGIN
SELECT
    ru.RuleName
    ru.RuleGroup
FROM RuleData.groupings ru
WHERE 1=1
AND   ru.ActiveRule = 1
AND ru.RuleOpen >= '2015-01-01'

via Chebli Mohamed