To add a layer to a new Timeline track without modifying any other layer in your project, use the Composite edit. The Composite edit places the layer in the track above the one you drag to.

1. Drag an item from the File Browser, Library, or Media list into the Timeline track area.

   As you drag, a tooltip appears at the pointer, indicating the current frame number.

2. When you reach the frame where you want the new layer to start, position the pointer over the layer you want as a background, holding down the mouse button until the drop menu appears.

3. Choose Composite from the drop menu.

   The new layer is composited into the project above the layer you dragged to.

To insert a layer into a new Timeline track and split an existing layer at the insertion point, moving it forward in time to make room for the new layer, use the Insert command. For example, if you insert a 100-frame movie into a group containing an existing layer, the new movie is added to the Timeline at the frame where you drop it, pushing the remaining frames of the original movie out 100 frames.

If you insert a new item midway through an existing layer, the existing layer is split into two layers, each on its own track.

1. Drag an item from the File Browser, Library, or Media list over an existing bar in the Timeline track area.

   As you drag, a tooltip appears at the pointer, indicating the current frame number.

2. Drag to the frame where you want the new layer to start, holding down the mouse button until the drop menu appears.

3. Choose Insert from the drop menu.

The new layer is inserted into the track, breaking the original bar into two, and pushing the frames after the insertion farther out in time.

To replace an existing layer with a new layer in the Timeline, use the Overwrite command.

If the new layer is shorter than the one currently in the group, the Overwrite option splits the duration of the existing layer and deletes only the frames where the new layer appears.

1. Drag an item from the File Browser, Library, or Media list onto a bar the Timeline track area.

   As you drag, a tooltip appears, indicating the frame number where you are located.

2. Drag to the frame where you want the new layer to start, holding down the mouse button until the drop menu appears.

3. Choose Overwrite from the drop menu.

The frames of the new layer replace the frames of the original layer. If the original layer contained more frames than the new one, the old layer is split into two layers and the additional frames remain.

To replace an existing layer with a layer of the same duration, use the Exchange command. The Exchange command is a variant of the Overwrite option, but instead of dropping the entire duration of the new layer into the project, the duration of the existing layer is used. For example, if you drag a 30-second clip over a 5-second clip, choosing Exchange swaps the existing 5 seconds with the first 5 seconds of the longer clip. If you exchange a longer clip with a shorter one—for example, swapping a 10-second clip with one that lasts only 5 seconds—the first 5 seconds are replaced, and the final 5 seconds of the original remain.

The exchange edit transfers any filters, behaviors, and keyframes from the original layer onto the new layer.

1. Drag an item from the File Browser, Library, or Media list onto a bar in the Timeline track area.

   As you drag, a tooltip appears, indicating the frame number where you are located.

2. Drag to the frame where you want the new layer to start, holding down the mouse button until the drop menu appears.

3. Choose Exchange from the drop menu.

The old layer is replaced by the new layer.

When you drag more than one item to the Timeline, the new layers appear in their own tracks above any existing layers. This is equivalent to performing a composite edit with a single object. A drop menu lets you choose whether the additional layers should be stacked up as a composite, or whether they should appear one after another (sequentially).

1. Shift-click or Command-click to select multiple items in the File Browser, Library, or Media list, then drag them to the Timeline track area.

2. Drag to the frame where you want the new layers to start, holding down the mouse button until the drop menu appears.

3. Do any of the following:

   • Stack the layers at the same start point: Choose Composite from the drop menu.

     Multiple layers are added to the project at the same point in time, each new layer on its own track.

   • Stack the layers in sequential order: Choose Sequential from the drop menu.

     Multiple layers are added into the project, each in its own track, one after another in the Timeline.

If you release the mouse button in the Timeline track area before the drop menu appears, a composite edit is applied by default. Alternatively, you can drop the multiple layers into the Timeline layers list. Doing so results in a composite edit.