Why is Lord Kartikey missing in Shiv Parivar pictures?

Why is Lord Kartikey missing in Shiv Parivar pictures? It is not as if Kartikeya is not worshipped or less popular compared to his family. There is a story why usually Skanda is not shown in the Shiva Pariwar. Well it is because when Shiva and Parvati were thinking whom shall be married first between Ganesha and Kartikeya. They decided that whoever can get one full round of the universe and come back, he will get married first. Kartikeya left on his peacock while Ganesha thought that if he goes on Mooshak, it will take time. So, Ganesha took round of his parents claiming that his parents are the whole universe for him. Lord Shiva annnounced that before any ritual or a good deed, Ganesha will be worshipped first and was married to Riddhi Siddhi. When Kartikeya got back, he got very angry and went to Srisail Parvat. Lord Shiva and Parvati then went to pacify him and meet him every Amavasya and Poornima respectively. That is why Kartikeya is mostly worshipped in South India as Murugan or Subramanian. Subramanian is said to be the ancestor of the Subramanian family. The festival of Thaipusam is very famous and Murugan is worshipped even in Malaysia and Singapore. The famous statue of Murugan and the temple of Batu Caves are in KL.