I'm new to Solidworks, coming from Inventor.  Using SW 2018.

I have assemblies that have large/complex sub assemblies (engines) so I would like to improve performance by speedpacking most of the engine geometry.

I've gone down to the sub assembly that contains the engine assembly, created a new configuration and added the speedpack.  But back in the main assembly, I can't figure out how to activate that new configuration (of the sub assembly).  I would rather not have to delete the sub assembly and re-insert it. 

So is there a way to update a sub assembly's configuration, from the parent assembly, if the configuration was created after it was inserted?