Buying new PPR with brother as partner. (Money Partner/JV/Group buying)

Hi all,

My servicing is hitting the limit due to size of portfolio and recently reduced incomes and my wife and I want a new PPR.(we currently rent)

My wife and I are thinking of asking my brother(who has NO properties) if he wants to contribute/invest.

He would not live there as he lives in a van(#vanlife is a thing) but it would give him a chance to enter the market in some way and make a return.

My wife and I have have substantial capital but low servicing.(and are not prepared to sell any of our portfolio as yet)

We would ask my brother for 20% of the Deposit funds(dep, stamps, lmi etc.) and 20% of the holding costs(rates, mortgage repayments, insurance) for a maximum investment 5 year period(and we would use his servicing to improve our borrowing power so that we can buy the PPR we would like).

The first 5 years we would have I/O mortgage, after which we would refi and give my brother 20% return on his money.

(or if we cant refi the PPR, I would give my brother a small unit I own, that he used to rent from me, depending on market value of the small unit)

QUESTION:

If we are returning my brother a 20% return because he contributed 20% of Dep and Holding costs, should it be 20% of the Capital Growth that has been made over the 5 years……………  or should it be 20% of the Market Value in 5 years?

(of course we would have an agreement with set rules/expectations and possible outcomes to protect each party in various scenarios)

Helpful thoughts, views, comments and experiences of this nature welcome. THANKS Team!