Fill down of multiple rows below selection

I'm trying to have the user select a few rows, then, because the rows have varying structures, fill down the entire row selection.
I'm running into trouble with the last line: autofill syntax or something.

NumRows = Selection.Rows.Count

'create space below the selection
Selection.EntireRow.Select
    Selection.Offset(NumRows, 0).Insert Shift:=xlDn

'Fill info from selection down
Selection.Resize(Selection.Rows.Count + NumRows, Selection.Columns.Count).Select
NumRows = "1:" & NumRows * 2 & ""
Selection.AutoFill Destination:=ActiveWorksheet.Range(NumRows).EntireRow, Type:=xlFillDefault