What starry_solo has suggested is called sponsorship and is extremely common. The most common arrangement is that the sponsor (you) pays for the event and, as such, is entitled to full control over the RSP and gets all event gifts. The sponsored (the person who is going in your stead) generally gets a free event credential and any pins he/she trades for at the event along with any nonshipable gifts, if applicable (usually just food), and is responsible for his/her park admission, transportation, meals, etc.
However, this is just the convention I have found over the years. Some sponsors have wanted more, with varying requests. I strongly suggest you and your sponsor discuss and come to an agreement about terms of sponsorship (and shipping the merchandise to you afterwards - Disney only will send frame sets directly from the event) before you make any changes to the event registration to avoid confusion and misunderstanding later on.