[GNC] Entering Stock Demerger, with reduced cost base

[xboxboy.mageia+GnuCash]

Hi all,

got myself another messy one. A stock was bought out, and part of that 
deal was it was broken into two companies just before.

Rather than issue/reduce shares held, it's been done on a value basis. 
Here's the basics:

Company FGL split into Company FGL and Company TWS, cost basis of FGL is 
79.96%, and TWS is 20.04%

Here's the office Australian Tax Office advice: 
https://www.ato.gov.au/forms-and-instructions/foster-s-group-limited-demerger-2011/background

At the time I had 143 FGL and gained 48 TWS shares. The FGL shares were 
sold for a total of $772.20

In my head I understand the concept: Entering it though... nope.

TIA