The law gives housing association tenants certain rights. Secure tenants have more rights than introductory tenants. You are an introductory tenant for the first year of your tenancy. After 12 months you’ll become a secure tenant.
You can add someone else to your tenancy. But, you need your landlord's permission to do this and your landlord can refuse in some circumstances. You don't have to add people who live with you to your tenancy.