My husband and I installed a semi-inground pool last summer and are working on finishing the concrete surrounding the pool this year. While preparing the ground for the concrete the pool light niche was accidentally broken. We have a pool liner and the pool is 2/3rd's full. We ordered a new light niche but now are trying to figure out how to install it since it needs to go behind the pool liner without having to drain the whole pool. Any suggestions? It is a Pentair Globrite Light Niche.