Lineages were retained in the form of clans with the clan leaders retaining their stations within the Zulu hierarchy. The largest clans saw their barons elevated to the station of Great Men of the Nation who were given important offices by the king and served as his advisory council. There were some northern barons who continued to run their clans as semi-autonomous nations within the larger Zulu Kingdom, up to and even including denying troops to King Cetshwayo during the Anglo-Zulu War.

For all that --with the sole exception of the abaQulusi who guarded the northwest-- all defeated peoples were made to join the Zulu military based on their age and not their clans. This broke down barriers and forged new identities. It was very common for a man to answer to his regiment name as a synonym for his own name, especially to strangers who might recognize his shield without knowing who he really was. By the time the king allowed each regiment in turn to sew on the headring, marry, and start a family and their own homestead, clan alliances still existed but service to the Zulu Royal Family was a heavy component of the social order. The Zulu Royal Family also invented and became to sole proprietors of umKhosi, the Festival of First Fruits, to which attendance was mandatory for all of their subjects and during which men arrived as part of their age-appropriate regiments and not as their regional clans.

Sources: Just about anything by Ian Knight, but if I had to pick one I would go with Anatomy of the Zulu Army. Also, John Laband's excellent Rise and Fall of the Zulu Nation would cover everything I've said in terrific detail.