Partnership with Family deal structure

[Mitchell Ellul]

In the upcoming months my mother and I are looking to buy a two bedroom condo as a primary residence for me, with a friend renting out the other room. My mother is putting down the 20% downpayment and will paying the closing costs. I will be paying my half of the rent and the other renter will be paying the rest. I am just trying to think of the best way to structure the deal to best value who has what equity in the house. Does anyone have experience in structuring a deal like this? 

Some notes: 

- If I were to move out we would turn it into a rental property investment (doing the calculations for viability before purchase)

- Me paying back the downpayment + closing costs is not a priority for her.

- To give you some numbers, we are looking at a 350,000 selling price, pre-approved for a mortgage rate of 2.59%, 5 year fixed term. Monthly mortgage payment is estimated to be $1118 per month.