Hi Berin

The answer should also depend on what's your intention to group these pieces together.

If the intention is to packaging and distributing, Paul's suggestion of two-layer charts should work. Another similar approach could be CNAB (https://cnab.io/) + charts, so CNAB could be used as the parent layer of your package. 

If the intention is to create a application definition for Kubernetes so you can declare dependencies of the components etc, then server side app model may be the solution, for example:  https://speakerdeck.com/resouer/oam-as-kubernetes-application-definition. In this case, you will have a helm chart to package a single app-config.yaml