In this paper we analyze the link capacity requirements for microwave backhaul architecture when two different Mobile Network Operators (MNOs) decide to "divide and share" their primary resource (working path) with each other as an alternative for investing in a backup path to reduce cost investments. To examine and to develop practicable performance bounds on resource sharing, we make an estimation of the resource utilization and derive integer linear programming (ILP) counterparts. Given the complexities of solving ILP, we also propose heuristic-based resource provisioning algorithm which allows MNOs to share their primary resource with (an)other MNO(s), without having to sacrifice their own traffic demand requirements. Illustrative numerical results show the effectiveness of our resource provisioning approach in terms of network resource utilization and connection blocking probability.