LEED-CS, CI or EBOM?

Hi, our client owns a building where there are two tenants, one occupying 75% and the other 25% of the total floor area. The tenant occupying the less area has been undergoing a renovation which the owner is doing and wishes for a LEED certification. However the renovation is almost finished and it might not be possible to achieve a high level or even certification. That sounds like a LEED-CI but it might be uncertain to achieve. On the other hand, the owner has some experience with LEED-CS/NC and is intressted to start working with LEED-EBOM and now is considering this rating system for this building. However the tenant occupying the largest floor area, 75%, do not wish to be involved to a possible certification. Two questions: 1) Is it still possible to go for a LEED-EBOM certification without the involvement of both tenants? 2) Is it possible to go for a LEED-CS for the whole building accounting only the renovation of the tenant occupying the 25% of the building?