Declare @TblFin Table 
(
Empid int
)

-- Inserting the Data in the Table 1 
Insert @TblFin 
Select 1 Union All 
Select 2 Union All 
Select 3 Union All 
Select 4 Union All 
Select 5 Union All 
Select 6 Union All 
Select 7 Union All 
Select 8 Union All 
Select 9

-- Table 2 
Declare @TblBgt Table 
(
EmpID int, 
PosID Int 
) 

--Inserting the records in the Table 2 

Insert @TblBgt
Select 1,1 Union All 
Select 2,2 Union All 
Select 3,3 Union All 
Select 4,4 Union All 
Select -1,5 Union All 
Select -1,6 Union All 
Select -1,7 

-- Now here i want insert all the missing empids in the my second table
i.e. @TblBgt and PosID will be MAx(PosID)+1 

So The Expected output when i do 
Select * from @TblBgt 

1	1
2	2
3	3
4	4
-1	5
-1	6
-1	7
5       8
6       9
7       10
8       11
9       12