Investing with family members?

hi everyone,
I'm a newbie here, and have a few questions I hope you seasoned investors may be able to help with.
I have a PPOR which I own jointly with a sibling. We currently owe about 50% of the value and have 50% in equity, and we are thinking of investing later this year. Another sibling who is struggling to enter the market would like to join us in this investing venture, and I would like to find out more about the risks associated with buying property with more than one co-owner. If 3 of us purchased an investment property, we could potentially buy in a better area as we could afford to spend more, but how would the tax benefits be worked out with 3 people? Also, are there additional costs? Would my sibling miss out on the FHOG because myself and my other sibling already own a property?
I understand we will need to seek advice from an accountant, but if anyone has any tips, ideas or knowledge I would be very grateful.
best wishes in acheveing your investment goals.
If you buy jointly, the bank will assess you as if you were liable for the whole debt. Your serviceability will be seriously affected.