This paper proposes an Integer Linear Program (ILP) to address Virtualized Network Function Forwarding Graph (VNF-FG) placement and chaining with Virtualized Network Functions (VNFs) shared across tenants to optimize resource usage and increase provider revenue. The proposed algorithm selects a limited number of candidate hosts from the infrastructure to reduce the complexity of the ILP and scale with problem size. Results from extensive simulations report performance improvements in terms of rejection rate, energy consumption and scalability. Limiting the number of candidates is an efficient heuristic to ensure scalability