Routing for Overlapping Segment Shared Protection (OSSP) in multi-domain networks is more difficult than that in single domain networks because of the scalability requirements. We propose a novel approach for OSSP routing in multi-domain networks where the underlying idea is the prior identification of potential intra-domain paths (or intra-paths for short) for carrying working and backup traffic between domain border nodes. The intra-path identification is subject to a complex model favoring bandwidth saving. These intra-paths are then viewed as virtual edges and help to reduce the multi-domain network to a simpler aggregated network. Routing is performed in this aggregated network at the intra-path level without going down unnecessarily to the physical links. The novel approach offers an exact and highly scalable routing thanks to the prior identification of the potential intra-paths and the introduction of the maximal share risk group feature. The experiments show that the quality of the proposed approach is close to the optimal one in single-domain networks and outperforms the previously proposed scalable solutions in multi-domain networks.