Don't do it. Unless you're buying an investment property with solid positive cash flow (in other words, no problems), and it's a long term legal partnership (LLC, etc...), that's not a relationship you want to get into with your friend. What if ish hits the fan and you need to sell your stake ASAP? You're S.O.L if your friend isn't also willing to sign off and sell the contract. He may say he would do it if the "worst case scenario" happened, but that's not in writing, and things change.
If you both want in, and want X number of points, just buy 2 separate contracts that add up to X points, and plan your trips together.
Trust me, real estate (commercial) is what I do for a living, and have for a few decades now. Those sorts of "friends buying a vacation home together" have a massive fail rate in terms of the friendship ending over something trivial in the long run, but it feels massive in the interim. $$$$ colors everything.
What a Debbie Downer I am in this post.....jeez. I'm depressed now. Lol.