Hello!
It is possible with the full version using custom fields (http://wooinvoice.rednao.com/getit/), honestly the documentation of custom fields is very poor yet =S (i have plans to improve it but i am busy doing other stuffs right now) so if you want i can send you the code that you need to add in your custom fields.
If you want to do this with the free version you would need to tweak the plugin, more specifically this file: woo-pdf-invoice-builder\smarty\fields\PDFTable.php.
PDFTable is the file in charge of generating the table. Please have in mind though that if you edit the file manually you would need to re apply the tweak, every time you update the plugin (because a plugin update overwrite the previous files).
Regards!
Hi Ed
Thanks for the detailed reply. Please send me the code to add custom fields. As I am doing this project for my NGO there are not much funds available. So I will try tweaking first if things wont work out, we might go and buy full version.
Thanks in advance
regards