I did my drive 10 years ago with a pattern that use standard 200x100 blocks
and 100x100 blocks in a different colour.
I didn't realise at the time that the 100x100 blocks where the thicker
blocks. That made it a bit of a pain to lay but it was finished ok.

I now want to dig up the front lawn and lay blocks over that. I don't want
to use the same pattern as before so I want to relay the existing drive with
a new pattern.

I assume that I can lay the new drive higher than the exising drive then
tamp it down to same level. Do I assume that the exising drive wont tamp
down any more so I simpley ralay the blocks on the old sub base. Then tamp
them to settle them in.

I will have to fill in the depression left by the 100x100 blocks though.