Does spark-splicing actually exist anywhere in the multiverse?
It does indeed. The Builders of Cybertron would carefully graft together the sparks of promising Maximals and Predacons together to create new ones, as a way of trying to bypass relying on the Terran Energon Matrix. The Maximal Windrazor, for instance, had his spark created through grafting fragments of the spark belonging to Dive Bomb, a veteran of the games, together with that of Phantomjaw, a member of the Predacon Secret Police. However, the practice never really caught on, as it required an enormous amount of energon.
After the Grand Uprising, it found new uses—first to create new Maximal and Predacon protoforms, and then in the development of Commandron and Maladroid mind-engrams. In the former case, two members of the Maximal High Council, long having been in love, decided to use spark splicing to help bring it into a newly manifest form. Two members of the Maximal High Council, long having been in love, decided to use spark splicing to help bring it into a newly manifest form. The resultant protoform, Tigerhawk, was the first protoform created on post-Uprising Cybertron, and was seen as a symbol of the newfound unity.
Unfortunately, even this peace couldn't last, and during the Second Vehicon Apocalypse, Tigerhawk found himself pressed into battle. He became a hero, and mourned the loss of his father.