Supply chain management is an expanding field, both in research and in practice. Performance in supply chains is adversely affected by the bullwhip phenomenon. We have considered a decentralised supply chain subject to delays with no reliable past sales data, as in the case of a new product and modelled the supply chain using system dynamics. The impact of shortage gaming on whiplash effect is evident from the first model. When no reliable past data is available, sharing of demand forecasts may not be credible, as seen in the second model. The third model depicts a case where the shared information is credible as in the case of a customised product. This system shows a better performance.