If you share ownership of a property, each shared owner is liable to all the mortgage debt in case of default. Also there are tax consequences that will be come rather complex for shared ownership.
On the other hand, you can make an arrangement to lend your friend money to buy part of interest for the property. For example, this could be put in writing as:
1. Party A pays Party B an initial payment of x0 and $x each month for y months.
2. Party A agrees Party B to live on the property free as payment of kind for the interest of the initial payment.
3. Party B repays Party A starting from year z with minimium payment of w% of the most recent assessed value of the property until the sum of all such percentage reaches 50%.
4. The property is consider in lieu for any outstanding liability Party B owes to Party A.
Since the amount of money involved is rather large, you might consider getting a lawyer to work it out.
On the other hand, you can make an arrangement to lend your friend money to buy part of interest for the property. For example, this could be put in writing as:
1. Party A pays Party B an initial payment of x0 and $x each month for y months.
2. Party A agrees Party B to live on the property free as payment of kind for the interest of the initial payment.
3. Party B repays Party A starting from year z with minimium payment of w% of the most recent assessed value of the property until the sum of all such percentage reaches 50%.
4. The property is consider in lieu for any outstanding liability Party B owes to Party A.
Since the amount of money involved is rather large, you might consider getting a lawyer to work it out.