2 linked inserts in one statement

[posh70]

I'd like to insert record into GROUP table, get autogenerated value group_id and then insert record into another table, USER, with this group_id as a foreign key.
Code below works perfect, but since this possibility is not documented, I'm slightly aware. Would you recommend this way or do you know a better way?
DB2 v8.1. If you are going to test this query in Control Center be aware that you need to run commit after this.
I've put DDL below. Thanks a lot !

with tmp1 as 
(select group_id
from FINAL TABLE (INSERT INTO GROUP (group_name)
     VALUES ('test'))),
tmp2 as 
(select count(*) as num
from FINAL TABLE (INSERT INTO USER (group_id, user_id)
     select group_id, 'test_user' from tmp1)
)
select num from tmp2;

DDL:

CREATE TABLE "GROUP" (
  "GROUP_ID" INTEGER NOT NULL GENERATED ALWAYS AS IDENTITY (  
		    START WITH +1  
		    INCREMENT BY +1  
		    MINVALUE +1  
		    MAXVALUE +2147483647  
		    NO CYCLE  
		    NO CACHE  
		    NO ORDER ) , 
   "GROUP_NAME" VARCHAR(30) NOT NULL);

ALTER TABLE "GROUP" 
	ADD PRIMARY KEY
		("GROUP_ID");
   

CREATE TABLE "USER" (
  "GROUP_ID" INTEGER NOT NULL , 
  "USER_ID" VARCHAR(64) NOT NULL); 


ALTER TABLE "USER" 
  ADD CONSTRAINT "GROUP_ID_FK" FOREIGN KEY
		("GROUP_ID")
	REFERENCES "GROUP"
		("GROUP_ID")
	ON DELETE CASCADE
	ON UPDATE RESTRICT
	ENFORCED
	ENABLE QUERY OPTIMIZATION;