When donors subsidize products for sale to low-income families, they need to address who to subsidize in the supply chain and to what extent, and whether such supply chain structures as retail competition, substitutable products, and demand uncertainty matter. Academic/practical relevance: By introducing and analyzing development supply chains in which transactions are commercial but subsidies are needed for affordability, we explore different supply chain structures, with product substitution and retail competition motivated by a field study in Haiti of subsidized solarlantern supply chains. Methodology: We incorporate product substitution, retail competition, and demand uncertainty in a threeechelon supply chain model with manufacturers, retailers and consumers. This model has transactions among the donor, manufacturers, retailers and consumers as a 4-stage Stackelberg game and we solve different variations of this game by using backward induction. Results: The donor can subsidize the manufacturer, retailer or the customer, as long as the total subsidy per unit across these echelons is maintained at the optimal level. Having more product choice and having more retail-channel choice can increase the number of beneficiaries adopting the products; this increase becomes more pronounced as demand becomes more uncertain. Managerial implications: Donors must coordinate across different programs along the entire supply chain. They should look for evidence in their collective experience for more beneficiaries when subsidizing competing retailers selling diverse substitutable products.