How to move hierarchyid subtree if the new parent has already got children? - sql

Question

I guess the problem is described in the title pretty well. I've got a table like this:
CREATE TABLE [Employees] (
[Id] INT identity(1, 1) PRIMARY KEY
,[Hid] HIERARCHYID NOT NULL
,[Name] VARCHAR(50) NULL
,[Secondname] VARCHAR(50)
,[Surname] VARCHAR(50)
,[BossId] INT FOREIGN KEY REFERENCES [Employees]([Id])
,[PositionId] INT FOREIGN KEY REFERENCES [Positions]([Id])
,[DepartmentId] INT FOREIGN KEY REFERENCES [Departments]([Id])
,[RecruitDate] DATE NOT NULL
);
And I need to change employee's boss from one to another. Obviously, there is a nice solution - GetReparentedValue(), and I used this example that seemed to be exactly what I needed.
But this solution happens to be not working. Hid.GetAncestor(1) is equal to previous BossHid. Probably, the problem is that it can't work well if new parent already got children. That really upsets me. Does it mean I need to write recursive CTE on my own?
Here is the code that was supposed to be working but it didn't:
CREATE PROCEDURE UpdateEmployee #Id INT
,#Name VARCHAR(50)
,#Secondname VARCHAR(50)
,#Surname VARCHAR(50)
,#BossId INT
,#PosId INT
,#DepId INT
,#Rdate DATE
AS
BEGIN
SET NOCOUNT ON;
DECLARE #BossExist INT
,#OldBossHid HIERARCHYID
,#NewBossHid HIERARCHYID
,#LastHid HIERARCHYID;
SELECT #BossExist = count(*)
FROM dbo.Employees
WHERE [Hid] = HIERARCHYID::GetRoot();
IF #BossExist != 0
AND #BossId IS NULL
RETURN;
SELECT #OldBossHid = (
SELECT [Hid].GetAncestor(1)
FROM dbo.Employees
WHERE #Id = [Id]
);
SELECT #NewBossHid = (
SELECT [Hid].GetAncestor(1)
FROM dbo.Employees
WHERE #BossId = BossId
);
SELECT #LastHid = #NewBossHid.GetDescendant(MAX([Hid]), NULL)
FROM dbo.Employees
WHERE [Hid].GetAncestor(1) = #NewBossHid;
UPDATE dbo.Employees
SET [Hid] = [Hid].GetReparentedValue(#OldBossHid, #NewBossHid)
WHERE [Hid].IsDescendantOf(#OldBossHid) = 1;
UPDATE dbo.Employees
SET [Name] = #Name
,[Secondname] = #Secondname
,[Surname] = #Surname
,[BossId] = #BossId
,[PositionId] = #PosId
,[DepartmentId] = #DepId
,[RecruitDate] = #Rdate
WHERE #Id = Id;
END
GO
Thank you.