Сombining two animations with different characters

I have a quite tricky question about combining animations.
So, I have this animation:

Each character has its own unique skeletons and so I can’t just merge them. When I interact with other characters I have an ability to grab them into sockets, but as I can see, there’s no ability to animate sockets to attach something into them. But, as I can see, some games has such thing.

For now I did this as follows: the second character has an animation where his root coincides with dragon’s root, so before it swallows, it turns off collissions, does cast to character, and moves his root into dragon’s root, combining both animations. But how I could make the same with just meshes? Does it mean I should make similar animations for each actor? I even wanted to make something like an additional blueprint with just one animation, and get a socket locator/rotator from it, so I could attach everything, but this way sounds quite tricky so I’m not sure about it.