HR Case Declarative Action for related cases

[heathers_]

I've created a declarative action to include an Add/Edit button on the related list in HR Agent Workspace. I need to relate sn_hr_core_case records. I need one for child case and another for related case. I've altered the script with different parameters but am receiving the same results. I receive the m2m slushbucket, however when relating case records together, I'm creating new cases with the sys_id in the number field. Also, the records are not populating in the related list. Are there suggestions or has anyone been able to accomplish this specific requirement using the modal feature?

function onClick() {
	var _strLink = 
		'/sys_m2m_template.do?' +
		'sys_is_list=true&' +
		'sys_is_related_list=true&' +
		'sysparm_collectionID=' + g_form.getUniqueValue() + '&' +
		'sysparm_query=&' +
		'sysparm_referring_url=' + location.pathname + '&' +
		'sysparm_stack=no&' +
		'sys_target=sn_hr_core_case&' +
		'sysparm_m2m_ref=sn_hr_core_case&' +
		'sysparm_collection=sn_hr_core_case&' +
		'sysparm_collection_key=sys_id&' +
		'sysparm_collection_label=SysID&' +
		'sysparm_collection_related_field=sys_id&' +
		'sysparm_collection_related_file=sn_hr_core_case&';

	var win = top.window.open(_strLink, '_self');
	
	win.focus();
}