Here is how you could do it:
There are a couple things this assumes. Only "master" will have rows that
may be inserted. If that is not the case, then this will mess you up big
time!

Sub MakeSame()
Dim DataArray(50000, 4) As Variant
Dim Fnd As Double
'pick the right line:
Windows("master.xls").Activate
'or
Sheets("master").Select

x = 1
Do While True
If Cells(x, 1).Value = Empty Then Exit Do
Fnd = Fnd + 1
DataArray(Fnd, 1) = Cells(x, 1).Value
DataArray(Fnd, 2) = Cells(x, 2).Value
DataArray(Fnd, 3) = x
x = x + 1
Loop

For Y = 1 To 2
If Y = 1 Then
'pick the right line below:
Windows("sheet2.xls").Activate
'or
Sheets("sheet2").Select
ElseIf Y = 2 Then
'pick the right line below:
Windows("sheet3.xls").Activate
'or
Sheets("sheet3").Select
End If
For x = 1 To Fnd
If Cells(x, 1).Value < DataArray(x, 1) Then
'insert a row and make it match
Rows(x & ":" & x).Select
Selection.Insert Shift:=xlDown,
CopyOrigin:=xlFormatFromLeftOrAbove
Cells(x, 1).Value = DataArray(x, 1)
Cells(x, 2).Value = DataArray(x, 2)
End If
Next
Next

End Sub