As said in the linked post, the hand signs are for the manifesting chakra, while weaving hand signs. More the shinobi's skill and chakra control increases, less the hand signs he needs to use. While techniques may require a number of hand seals to work, a skilled ninja can use less or even one to perform the same technique.
In the whole series, we've seen shinobi using hand signs with two hands, one hand and even no hand signs, which requires a very precise control of chakra. As mentioned in this post, at various instances shinobi of great skill like Itachi, Minato, Sasuke or Naruto used even one hand signs or no hand signs.
But When using hand signs with another participant, they both need their chakra to be in perfect sync with each other and should have a great control over it. That's why Naruto and Sasuke could accomplish some jutsu.
Also, there were instances, like in Obito Uchiha using Kakashi Hatake's hand for the Fire Release: Great Fireball Technique or Anko Mitarashi using Orochimaru's hand for the Twin Snakes Mutual Death Technique. For these instances, a shinobi needs to have a great amount of chakra, which he forces to make it flow into other participant's body and gains control of other's chakra (momentarily) to get his jutsu done.
Hope this answers your doubt. :)