As I mentioned in variation point 2, I did in fact try this. However, when I carefully compared my code with your suggestion, I noticed that you were calling BindToObjectByDNEx() on the parent group, not on the member group. So I modified my Custom Command as follows:
$groupDN = Get-AdmGroup -Filter 'Name -eq "role_AlexTest21"'
if ($groupDN) {
$group = $Context.BindToObjectByDN($groupDN)
$parentGroupDN = $Context.TargetObject.Get("DistinguishedName")
$parentGroup = $Context.BindToObjectByDNEx($parentGroupDN, $True)
$parentGroup.Remove($group.AdsPath)
}
This worked! The BR is now being triggered.
Note that just using $Context.TargetObject.Remove() in the script was failing to trigger the BR, presumably because that variable bypasses the Adaxes pipeline. By rebinding using the "Ex" version of the function, the object reference is now in the pipeline, and calling Remove() on it works as expected.