We consider a multi-retailer system where the sellers are connected with each other via a transportation network and the transactions with the consumers happen on a platform. Each consumer is serviced by only one retailer. Since the demands to the sellers (i.e., the retailers on the platform) are stochastic in nature, supplies can be either in excess or in deficit. Transshipping these items laterally among the retailers benefits both, the platform and the retailers. For retailers, excess supply leads to wastage and deficit to a loss of revenue, while via transshipment, they get a better outcome. The platform can also earn some revenue in facilitating this process. However, only the sellers know their excess (which can be salvaged at a price or transshipped to another seller) or the deficit (which can be directly procured from a supplier or transshipped from another seller), both of which have multiple information that is private. We propose a model that allows lateral transshipment at a price and design mechanisms such that the sellers are incentivized to voluntarily participate and be truthful. Experimenting on different types of network topologies, we find that the sellers at more central locations in the network get an unfair advantage in the classical mechanism that aims for economic efficiency. We, therefore, propose a modified mechanism with tunable parameters which can ensure that the mechanism is more equitable for non-central retailers. Our synthetic data experiments show that such mechanisms do not compromise too much on efficiency, and also reduce budget imbalance.