@heisenmatt
each share for CGT purposes is a separate asset
if you wish to qualify for the 50% CGT discount, you must hold the share for over 12 months
if you own different parcels of shares in the same company, you can choose/nominate which shares are subject to a sale
in other words, you do not have to use a 'first-in-first-out' method (as long as you can identify the shares sold in your records)