Magento 2: How can I get the parent UI Element?

I am not 100% sure it is the right way to do it and not 100% sure it will work for components as containers.

In the past I used this.containers variables to refer parents.

i.e.:

this.containers[0]

Otherwise (and suggested way):
If you need this to make children to communicate with parent you could use an external model class used as singleton and required from both parent and child.

In this way you can store common information or send/receive messages.

In the past I solved this way.

UPDATE with Giel Berkers comment (see below):
Another good approach could be using uiRegistry to share inforamtion between modules.

This approach is suggested when the inforamtion you need to share should be considered global.