I ditto what other people are saying, they basically want to buy some property that appends their property, and have other people pay a portion of the mortgage downpayment (plus 40% of mortgage payments!) for a charity endeavor that only exists in their mind. The bottom line, they could do this, solicit donations, and then try to do the charity and quit after a year, or never even get around to it. And the result is that they get a bunch more property in their name, but nothing legally preventing them from just keeping the land for their own enjoyment, or even selling some of it, or even paying people back.
If they were serious, they would work on the charity part first, as in create a charity, work on the aims of the charity (helping immigrants, at risk kids) in already existing locations including their own property, to show proof of concept), have a board, create a business plan. then at that time they can actually solicit donations for an actual charity, from the public, other businesses, etc.
Right now if you do help, you are simply giving money to a family member to buy some land next to their house. That's it. In that case their approach should be, we really want to buy this land but we are cash strapped, we want to take out private loans to bridge the gap.
In that case I would also say no. As they state, they need help both in reducing the initial capital amount of the mortgage by asking for interest-free loans from people. No interest payments. AND no guarantee of being paid other than the relatives promise.
AND even with reducing the mortgage amount, they still have a shortfall of 40% to pay the monthly mortgage payments. that is NOT a small gap. The charity part makes it even more iffy truth be told. Charities, especially new charities, are not known for being money-makers. They don't even know what the operational costs to run such a kind of charity. That's in adiition to known mortgage payments, needed investment in property, repairs, insurance etc.