Graft Bones

Splice another take's movement onto part of the skeleton - a baked Layered Blend Per Bone. The body keeps playing take A while the head, an arm, or the face plays take B. Output suffix: *_Grafted.

Use cases straight from the mocap trenches:

• The run cycle is perfect but the head look is wrong - graft the head branch from a different take.
• Same body performance, different attack - graft clavicle_r down from each attack take to build variants.
• The shot is good but the facial expression isn't - graft the facial bone branch from a better take.

How it works

• Local bone space: the grafted branch rides on whatever the target's body is doing - exactly like the Layered Blend Per Bone node, but baked into a real asset that drops into montages and blendspaces.
• Two frame windows: take source frames [from, to] and land them on target frames [from, to]. Different lengths (or frame rates) are fine - the source window is retimed to fit, with fractional-frame interpolation.
• Seam blending: the graft fades in/out over Blend Frames at the target window's edges, so there's no pop where takes meet.

Options

Option	Meaning
Same Skeleton Only	Filters the picker to takes on the target's exact skeleton (default on) - retargeted libraries are full of same-named takes on other rigs. Uncheck to browse everything
Source Animation	The take to graft from
Source Start / End Frame	Source window (inclusive) - sliders capped to the source's length, auto-filled to the whole source when you pick one
Whole Clip Per Take	Graft across each target take's own full length - on by default when more than one take is selected (see below)
Target Start / End Frame	Where the graft lands (prefilled to the whole clip). Greyed out while Whole Clip Per Take is on
Mode	Replace swaps the branches' motion for the source's; Add on top layers the source's sway/motion onto the target (see below)
Bones	Branches to graft - each entry replaces the bone and everything beneath it
Blend Frames	Fade width at the window edges (default 5)
Create New Asset	New *_Grafted copy (default) or in-place rewrite

Root motion is never touched unless you explicitly include root in the bone list. Float curves, notifies, and sync markers stay the target's own.

Grafting a batch

Select several takes and one graft lands on all of them. The frame fields describe the first take only, so a single window cannot serve a batch of takes with different lengths: a 30-frame window covers all of a 30-frame take and less than a third of a 100-frame one, which keeps its own motion for the rest.

Whole Clip Per Take resolves the window per take instead - each one is grafted from its first frame to its last. It is on by default for a multi-take selection and off for a single take; untick it to apply the explicit window to every take on purpose.

Cross-skeleton grafting

The source doesn't have to live on the same skeleton asset - bones are matched by name. Uncheck Same Skeleton Only and any take whose branch bones share the target's names grafts fine (the usual case: the same rig imported twice, or takes retargeted onto a naming-compatible skeleton). Translations are scaled by the rigs' size ratio (measured from pelvis rest heights), so a bigger rig's offsets don't deform a smaller one - the result note reports the ratio. Add on top mode is the most robust cross-skeleton, since it transfers deviations rather than absolute pose.

Genuinely different rigs (other hierarchy or bone names - Mixamo vs MetaHuman) are a job for UE's IK Retargeter first; graft the retargeted result.

Bone tracks only

Grafting copies bone animation. MetaHuman faces are bone-driven (FACIAL_*), so the facial use case works; rigs whose faces run purely on float curves (ARKit-style) would need their curves copied separately.

Add on top (additive layering)

In Add on top mode the source's motion doesn't replace the target's - the source's deviation from its own window-average pose is layered onto whatever the target is doing. The source's base pose stays out of it; only its movement transfers. Output suffix becomes *_Layered.

• Layer a breathing/sway idle onto a stiff aim pose
• Add a flinch or shiver on top of any clip
• Put subtle head bob from one take onto another's performance

Compose with Isolate and Smooth

Isolate Bones turns takes into clean single-purpose overlay sources; Graft splices them together; Smooth Bones with a frame window cleans any residual seam.

Scripting:

ok, err = unreal.TakeForgeLibrary.graft_bones(
    target_seq, source_seq, ["neck_01"],
    source_start_frame=30, source_end_frame=90,
    target_start_frame=45, target_end_frame=105,
    blend_frames=5.0, add_on_top=False)