MasterID
1
2

ID  MasterID    DetailsDescription
1      1        XXXXX
2      1        XXXXX
3      1        XXXXX
4      1        XXXXX
5      1        XXXXX
6      1        XXXXX
7      2        XXXX
8      2        XXXX
9      2        XXXX
10     2        XXXX
11     2        XXXX
12     2        XXXX
13     2        XXXX
14     2        XXXX

ID  MasterID    DetailsDescription
1      1        XXXXX
2      1        XXXXX
3      1        XXXXX
4      1        XXXXX
5      1        XXXXX
6      1        XXXXX
       1        NULL
       1        NULL
       1        NULL
       1        NULL
7      2        XXXX
8      2        XXXX
9      2        XXXX
10     2        XXXX
11     2        XXXX
12     2        XXXX
13     2        XXXX
14     2        XXXX
       2        NULL
       2        NULL

DECLARE @MasterTable TABLE(MasterID INT)
INSERT INTO @MasterTable
VALUES(1),(2)

DECLARE @DetailsTable TABLE (ID INT, MasterID INT, _Text NVARCHAR(255))
DECLARE @X INT=1
WHILE @X <7
BEGIN
    INSERT INTO @DetailsTable VALUES (@X,1, 'XXXXX')
    SET @X+=1
END

SET @X=1
WHILE @X <9
BEGIN
    INSERT INTO @DetailsTable VALUES (@X, 2, 'XXXXX')
    SET @X+=1
END

DECLARE @TEMP TABLE (M_ID INT)
DECLARE @ID INT
INSERT @TEMP SELECT DISTINCT MasterID FROM @MASTERTABLE
WHILE ((SELECT COUNT(1) FROM @TEMP) > 0)
BEGIN
    SET @ID = (SELECT TOP 1 M_ID FROM @TEMP)
    INSERT @DETAILSTABLE
     SELECT TOP (10 - ISNULL(NULLIF((SELECT COUNT(*) FROM  @DETAILSTABLE WHERE MASTERID = @ID) % 10, 0), 10))
    (SELECT MAX(ID) FROM @DETAILSTABLE WHERE MasterID = @ID)+n, @ID, NULL
    FROM (VALUES(1),(2),(3),(4),(5),(6),(7),(8),(9),(10)) A(n)
    DELETE @TEMP WHERE M_ID = @ID
END

SELECT * FROM @DETAILSTABLE ORDER BY MasterID, ID