My sister is buying a home with a cousin.  They're both figuring that it will be nice to have their rent go toward something instead of out a window.

But here's the thing.

They want to get a duplex, and my cousin is figuring he'll take the smaller apartment (any duplex USUALLY has one apartment that's a different size from the other).

Now he's thinking that since the place they've decided on has a considerably smaller upstairs (about 70% the size of the first floow apartment) that he should pay less of the mortgage.

Of course my sister, by having the bigger place, will pay a lot more in heating costs.

She's willing to pay more, but not quite as much as he'd like her to pay ($800 to his $600).

So the question is this, what do you think is fair in a situation like this?

I mean, they'll own the home together, so when they sell down the road they both stand to make a profit off the equity. 

I told her if she agrees to that kind of split then she has to get it in writing that she owns the bigger percentage of the home too.

But is that fair?  Since she's actually using more of the space should she pay more and still consider it even as far as ownership?

I'm just not sure.  On one hand I think of it as an investment and it should be 50/50, but on the other hand she is getting use of the nicer apartment, there is some value in that right?

I have to run out and look at the car, but I'm really curious what all your thoughts are on this.  I'll check em' out when I get back.