Sequencer attach function has 4 modes that are problematic for doing shots. An object is carefully placed near/on another as the user wants, just like as kids we placed items to be glued precisely. But Sequencer attach functions ignores all of that. Default is None which simply flings the object you wish to attach halfway across the level from where you want it and where you placed it. The other modes all do some variation of this in different ways. Even the Preserve Current rotates the object. In some cases you can hit the reset location/position if you’re lucky.
Here’s a shot that currently seems to be impossible to do with the attach function.
Take a sphere and apply a World map to it. Now place and rotate it exactly as you want for a shot.
Carefully animate the hand of a metahuman to grab the sphere. Now use the attach function.
Even though everything’s been lined up the object will jump and or rotate. It may move the center of the object to the hand bone or socket you added. Or it may rotate it. In any case it seems to require the user to manually move and rotate in 3 dimensions and toggle back and forth to the previous frame to try to achieve some type of alignment to what it just was. And if at some point it needs to unattach or attach to a different object you will need to repeat the same manual process.
My suggestion is to add another mode that doesn’t move the object at all. The system simply records the relative position and rotation of the object and the object it’s being attached to. This would allow seam less transition between ‘attached’ and unattached.