How do add a new host to an existing config_group using ambari API

[#1]

I'm adding a new node to a cluster and adding and installing some services to the node using Ambari API, and that's well documented, for example here. Now I have a special case where I want to add a service, like Node Manager to a specific, non-default, already existing config group. I don't want to change the config group other than adding my host to it. What's the call, or a sequence to that?

[#2]

I guess I can try the approash from here, getting a desired config group settings, inserting my new host in it, and uploading to Ambari using PUT. And doing this after adding the host_component but before installing it?