1. Proposed title of this feature request

?? this works from the UI so it;s not a completely new feature. it just needs to work declaratively

2. What is the nature and description of the request?

We would like to enable this use case:

1. a customer has various pools of servers (let's say datacenters/envs). These pools of servers are mapped to InfraEnvs.
2. new serves can arrive at anytime and will be mapped to BMHs belonging to those InfraEnvs. Each BMH can belong to one InfraEnv of course.
3. platform admins create OCP clusters or add nodes to existing OCP clusters from the InfraEnv inventory picking available BMHs. They don't necessarily use all of the BMHs in an InfaEnv, this is what requires the late binding feature.

notice this today works from the UI, but it does not work declaratively: i.e. creating a bunch on manifests.

3. Why does the customer need this? (List the business requirements here)

It seems logic that there is a function at the customer that purchases, racks and stacks new hardware and makes it available for OCP bare metal clusters, and then there is another function that decides what to do with that spare capacity.

4. List any affected packages or components.

The technical issue is the following: When creating a bare metal installation declaratively, the ClusterDeployment and the AgentClusterInstall CRs collaborate to describe the new desired cluster. In these CRs there is no way to select a subset of the BMHs that are in a InfraEnv (you can only select all of them).
To be comprehensive there is a BMH selector (see below), but it does not work, it looks like that feature was abandoned.

platform:
  agentBareMetal:
   agentSelector:
     matchLabels:
       cluster-name: pool4

Give this status quo, the only way to add some BMH to an installation is to patch the Agents corresponding to the desired BMHs, setting the reference to the ClusterDeployment name.