Parlays are predictions: when you send a new parlay to someone, you are saying, "I think X will happen, and I might give you Y if I'm wrong." When the receiver taps the "Parlay" button, they are saying, "I think you're wrong, and I might give you Y if X doesn't happen." All monetary transfers are voluntary, optional gifts.
Parlays are not agreements, contracts, understandings, or bets. The Parlay app cannot be used for betting or gambling. There is no guarantee that parlays will not be canceled by a participant, that outcomes will be judged fairly, or that gifts will be given.