As Mowgli and Melody are from different series, they have never met in canon. Even though a few Disney crossover video games could have the two dark haired kids cross paths with each other or get them added in the same team, by the player's choice.
Throughout their Disney films, both Mowgli and Melody commonly walk around barefoot, as well as them feeling most happy in places that they were told to never go near. The jungle being the place where Mowgli was raised in among its animals and has friends that reside there, while Melody feels strongly draw to the sea like how her mother was drawn to the land. Her mother's mermaid origins could be the reason why Melody is able to understand certain kind of animals that live under or close by the sea, while Mowgli's time in the jungle allowed him to learn its many animal tongs. Which is why both young, black haired Disney characters get along with animals than they do with people.
In Mowgli's second Disney film, he tries to share the beauty and frills of his former jungle home with the other children of the man village, but the dangers of it is what kept the adults from listening to Mowgli and when he was offered a chance to go back into the jungle he took it. In the end, however, Mowgli goes back to live in the village, but from time to time he and his friends sneak into the jungle to have some fun with their animal friends. While the only reason that Melody was kept away from the sea was due to an incident where her young life was placed in danger, and her family were worried that they wouldn't be so lucky next time. When Melody's mother found out about her secret dives in the sea and became upset about it, she met someone who gives her a chance to live in the sea as a mermaid. In the end Melody was given a choice to live with her grandfather in the sea or to remain with her parents on land, she came up with the better idea that allows all of them to be together, without a large wall keeping their worlds apart.
Mowgli's Disney film is based on the book of the same name where he shares the same name as the character he is based on, while Melody's is the sequel to The Little Mermaid, where the first film is based on a fairy tale of the same name.
Mowgli and Melody are shipped by a small group of fans who believe they would get along very well. Also that both are extraordinary people. Mowgli being born and raised in the jungle and with wolves, while Melody born around mermaids and the ocean.
In many fanfictions, Melody goes to live with Mowgli in the jungle and ends up loving it more than the ocean. There have even been those who feature them as a young Tarzan and Jane, or have placed Mowgli as a prince that meets Melody when she and her family visit his country and kingdom.