I was just covering many of the possible issues that come up.
From your specific details, the documents will show that your friends are receiving gifts. They are then making gifts to you, and you are using them for medical expenses. None of this is taxable, and in fact, you can still take a medical expense deduction (if you otherwise itemize your deductions) for expenses you pay with gifted money.
The issue for your friends is that they may receive a 1099-K from GFM, depending on the total amount of the transaction. Although it is not taxable income, the IRS may assume it is taxable income unless they prove otherwise, so they should keep good records of everything that happens (document the original posting, emails, canceled checks and bank records of the withdrawal to them and the checks to you, etc.)
