Question about exiting/timeframes with cross collateralization

Hi everyone,

Fiancee and i are still in the process of house hunting and sorting out our finances.

A mortgage broker we recently contacted has suggested that we take out a joint mortgage with 95% in my fiancees name and 5% in mine.

He (my fiancee) does not own any property and is eligible for the FHOG and no stamp duty for less than $500k (we are in nsw).

I own 2 properties and am not eligible for any of the above. The broker has suggested that we use my 2 properties and x-coll. He has suggested a product through ANZ. Now I am fully aware of the risks and have read many interesting posts in these forums about X-coll.

I want to make an educated decision with this as i am looking to refinance both my mortgages at some point this year as well.

I guess my question is- if we did go down this path, how long are these contracts generally for? 5 years? Less? More? I would be fine with starting off our mortgage this way but it is not something i would want to continue with for more than a few years. Plus, if we decide to split the loans up later on, how would that work?