I have 2 worksheets each with an unknown number of rows which I want to move
to the third worksheet as follows

Sheet 1 data in rows 1 to 15
Sheet 2 data in rows 1 to 23
Sheet 3 to contain Sheet 1 rows 1-15 in rows 1 - 15 with
sheet 2 rows 1 - 23 in sheet 3 rows 16 to 38
Automatically if possible but I don't know how many rows will be in each of
sheets 1 and 2