Ok - not so hard
Edit the file administrator/components/com_easylayouts/output/common/custom_field.php and add these new lines
foreach (array("subform_wrappertop", "subform_wrappertop") as $wrapperfield)
{
$field[$wrapperfield] = str_replace("{ID}", isset($item->id) ? $item->id : "", $field[$wrapperfield]);
}
at line 34 just after
$field["subform_wrappertop"] = str_replace('{FIELDNAME}', $heading, $field["subform_wrappertop"]);
$field["subform_wrapperbottom"] = str_replace('{FIELDNAME}', $heading, $field["subform_wrapperbottom"]);
Then change your wrapper HTML use use
collapseExample{ID}
I'll include this change in the next release of EasyLayouts