2 Pavlinho
Probably they were tying one skeleton to the bones of another. But I don't know how it's done.
If I understand correctly, comrade Zobr does many such things simply brilliantly.
In Rome 2, I once transferred the animation of a human to the animation of an elephant, so that there were two people on the elephant, a driver and an archer....well, I'm not a 3D master, I got tired of doing it, because at least in Rome 2, as far as I know, the skeleton has to be a single whole, and if you take the animation of one skeleton and attach it to the root bone of another, the animation is distorted, so I had to use tricks......well, I had to connect about 30 animations....