Hi,
Something like this should help.
... the SQL is untested, but it should get you most of the way there.
SELECT
t.UserId
,t.UserName
FROM
(
select 1 AS OrderColumn, b.UserId,b.UserName from Users b where b.UserId='e47277ab-5c62-4311-80f9-b5705fd075f6'
union
select 2 AS OrderColumn, a.userId,a.UserName + '-' + a.FirstName + a.LastName As UserName from Users a
where a.ParentUserId='e47277ab-5c62-4311-80f9-b5705fd075f6'
) AS t
ORDER BY
t.OrderColumn
;