In the future, posting the sample data as a create table script with inserts for the sample data would help us out quite a bit (otherwise to test solutions we need to manually get all that data entered somewhere).

Here's a good link on how to do that: https://spaghettidba.com/2015/04/24/how-to-post-a-t-sql-question-on-a-public-forum/

Anyway, perhaps something like this is what you're looking for?

IF OBJECT_ID('tempdb.dbo.#companies') IS NOT NULL DROP TABLE #companies;

CREATE TABLE #companies
(
CompanyName varchar(20),
CompanyStatus varchar(20),
CompanyNumber varchar(10),
GroupNumber varchar(10)
);

INSERT INTO #companies
VALUES
('Blackwell', 'group','A123G','A123'),
('Symphony','subCompany','s678','A123'),
('Blends','subCompany', 't123','A123'),
('Tiger', 'group','T123G','T123'),
('Pepper', 'group','Z987G','Z987'),
('Great Falls','subCompany','f545','T123');

WITH  ordered_parent_companies AS
(
SELECT GroupNumber, rn=ROW_NUMBER() OVER (ORDER BY CompanyName)
FROM  #companies
WHERE  CompanyStatus='group'
)

SELECT c.*
FROM  #companies c
   INNER JOIN
   ordered_parent_companies opc ON c.GroupNumber=opc.GroupNumber
ORDER BY rn ASC,
      CompanyName ASC;

Cheers!