I am a tenant, and my landlord is a SCI (real estate investment company). Can the partners give me notice to move out in order to house a relative?

Yes. According to Article 15 of the law of July 6, 1989, the landlord can give you notice at the end of the lease with proper notice and justification, particularly for the purpose of housing a close relative (such as descendants, ascendants, or a PACS (civil union) partner. Article 13 of the same law stipulates that when the landlord is a civil company exclusively made up of relatives and in-laws, they can give notice to the tenant to recover the property to house an associate.