You can copy load combinations between analysis models within a physical model. You can also copy between physical models if they have the same environment and load groups.
First you need to save the load combinations that you want to copy to a .lco file. If you want to make the load combinations available in another physical model, you need to copy the .lco file to the \attributes folder of the destination model, or to the project or firm folder. Then you can load the load combinations to another analysis model.