In his Dear Economist column this week, Tim Harford counsels someone who let his sister take a 30 percent share of his mortgage but now wants to have more than 70 percent of the equity. Harford correctly thinks that that is a bit rich as he got to actually live in the house. If anything, the equity should flow the other way.
What was interesting was why they entered into this arrangement. Apparently, his sister wanted a stake in the property market as a hedge for some future full entry into it; say, when her income rose further. Of course, buying a share of a specific property is risky in this regard. Better to buy some share of a residential property fund. In Australia, such funds exist now thanks to Rismark of which I am an advisor. That way you can access the property market as a hedge and avoid the family disputes that require public advice from economists.