A blend being used as a library can contain more than one model.
For this tutorial, I'm using Library_Trees_Start.blend.
Position your model in the library blend
When Blender 3D adds a model from a library, it doesn't use the model's object center as the group's object center. By default, it uses the World Coordinates[0.0, 0.0, 0.0]. This can be changed.
Create a new group.
For library linking to work, the object/objects must be in a group. No group. No library linking.
PalmTree-Trunk selected: Object mode
Buttons Window menu >> Object (F7) >> Object buttons
Object and Links tab
Add to Group button
The Blender 3D and game engine tutorials were created as a series of step by step instructions and help you create computer games. Use the tutorials to make casual video games, First Person Shooter games, role playing games, racing simulation games and more. Use the tutorials as a self paced learning tool to model and program your own three-dimensional world and then play on your computer.