In some cases it would be very useful to be able to group the hosts, created from host prototypes by host groups from LLD macros, even if the host groups are created from different LLD rules on different hosts.
Consider a case, where an LLD rule returns a macro

{#CLIENT}, which contains CLIENT1 and from this, we create a host and host group "CLIENT1".
Then, on another host, another LLD runs, also returns macro {#CLIENT}

with the same value, but is unable to create a new host group and doesn't add to the existing one.
This would be very useful, to group all discovered hosts for this specific client.