Thanks for the advice guys
I think i will definitely look into the costs involved in getting out of our fixed term loan as the offset account on our home loan for the 50k sounds like the way to go but is not available with the current loan, might be able to get some discounted exit costs if starting up another loan with same finance company.
From the research I have done on similar duplexes for sale in similar areas, each unit will be worth around 330k conservatively, also the costs I mentioned will be absolute maximum at this stage and the more we speak to different builders the more money we will be able to save in different areas. eg to not go the full turn key package, get some contractors that I know to do a few of the finishing off like floor coverings, concreting, landscaping etc.
I understand that I could maybe afford to do the whole thing myself and leave my parents out of it, and also that I could buy another investment property for a lot less effort, but we have a few reasons we think are good ones but thanks anyway.
It was mainly to get your opinions on the finance side of things, and the best way to set it up
Thanks