Quick question, i have a player with a hand. The hand is not attach to the player and can be trow in front of the player (Character design, don’t ask 
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But i want the be able to create a beam particle between the hand and the player. Is there a way to attach (by blueprint or programming) the source to one bone and the target to another bones ?
You can use the ‘Set Beam Source Point’ and ‘Set Beam End Point’ on each tick to a new location - I haven’t worked much with sockets but it looks like the ‘Get Socket Location’ will let you find the world location of specific sockets. Then it would just be a matter of setting the source and end points to the socket locations on each tick.
Hope that is what you were asking!