As a Roblox developer, it is currently impossible to replicate Procedural / IK Animations from client to server without using Motor6D(s) and RemoteEvent(s)
The only way to replicate Motor6D’s from client to server, at the moment is the use of remote events but this can cause network traffic when there a lot of Players
PS: if this is not possible then I would like to request a new constraint that is riged and works like a Motor6D