Large penetration of renewable resources creates new challenges for grid operators. The recent FERC ruling on transmission asset depreciation highlights one of the impactful but understudied issues, transmission asset usage and depreciation. Change in line usage can be accounted for by rewarding or penalizing the market participants directly. However, the impact of large penetration of distributed energy resources such as rooftop solar PVs (which do not participate in the electricity wholesale market) on transmission flows needs indirect solutions. This work proposes a market adjustment technique using virtual loads to mitigate the change in line flows caused by distributed resources in multi-area systems. Optimal virtual loads needed at each bus in the day- ahead planning to limit the line flow to a desired level are determined using power transfer distribution factors. The simulation, conducted on a modified IEEE RTS-96 system with real load data and estimated solar data, demonstrates that the average total line flow difference can be mitigated in multi-area network, while the average total conventional generation cost remains largely unchanged. This result shows that the method is highly effective in substantially reducing the transmission line impacts caused by distributed resources. This research was mainly motivated by transmission utility in western Kansas as they have experienced a difference in revenue.