ah, you may want to fix the page then because I could see people sending payments before they insert their address and click update. Some may pay without inputting their address and you'll have no idea who it was. They'll lose their money.
You have exactly 24 hours to update your address, besides, it will check the database based on your IP address if it had any earlier investments. If it did, it will use that address. My total idea was: "An unique total automated anonymous lottery", and without filling in forms etc. That's why you get your payment address. All payment addresses are bound to an IP address (you can try), so if they send a payment and come back later, they will still have the same address and the opportunity to update their address.
Umm, I wouldn't do that. Some people use proxies and TOR especially if your goal is an "anonymous lottery". You'll have multiple people looking like one. Someone is going to get their address changed.