Reimport All seems to be needed -- any alternative?

I have an asset for sale in the Asset Store, the NPC Populator, which requires the animation clips from the Standard Assets. If my asset is loaded first, then the sample scene is opened, then the Standard Assets are loaded, my animation controller does not recognize the animation clips.

If the sample scene is not opened before loading the Standard Assets, this problem does not happen.

If the Standard Assets are loaded first, before my asset, this problem does not happen.

Running Reimport All, or restarting Unity, fixes the problem.

Is this expected behavior? If so, is there a better way to manage this kind of dependency between my animation controller with animation clips that are imported separately?

Thanks for any insights!
Brion