Providing that you can add them to one fbx armature that you imported this one armature has animations of others as well.

So, after importing all Mixamo downloads into Blender save them as actions and you can remove all the armatures except one.

However, by redoing these actions for each imported armature, you can build a pool of actions.

You can modify these keyframes into Actions by pushing them down with a mouse cursor.

Here the orange bar symbolizes the keyframes of the Armature that you have imported.

By clicking the View icon, you can have access to the NLA editor and can see this interface.

Such as you can use Mixamo’s default format and import FBX files. It is quite simple to download a clip from Mixamo, you just need to do the import function from within Blender after you have chosen exported format in local drives. In this article, you will find several ways to use the Non-Linear Animation editor in Blender 2.9 to help bash animations from Adobe Mixamo. Thus, provides an exceptional way to mix animations with the option of adding personal flair to them. Ways to Combine Mixamo Animation in Blender 2.9

Gratefully, Blender’s NLA editing system allows blending clips and you can also edit them. Moreover, it saves time and workS for any animated filmmaker. It provides free services and from a browser. One such sensation is Adobe’s Mixamo, which enables you to upload a mesh that is automatically supplied and animated from a vault of motion-capture animations.

Mixamo blender