Duoplex

undefined: A Duoplex or Duplex is a two or more systems who are linked in a way that they may share an innerworld, it may be fully combined, or linked in another way (gates, portals, doorways, ect.)

This link doesn't have to be romantic unlike an Amor System, it can be any type of link (Familial, Platonic, Romantic, Ect.)

Most commonly, Duoplexes have known each other for years before they link, though that's not always the case. Most Duoplexes consider themselves one system shared over multiple bodies.