Ok, you are right @Robin S. I think, now i understand you. ?♂️ Your idea to use a field for the parent-child relationship works great:
I add a empty repeaterfield to template. In ready.php i add to a edit button (each children page) include pagination. It looks like it´s a repeater field items (old page situation). All happy.
$this->addHookAfter('Inputfield::render', function (HookEvent $event) {
$field = $event->object;
$form = wire('modules')->get("InputfieldForm");
//get edit page
$page_id = $this->input->get('id');
$page = $this->pages->get($page_id);
//add child pages to empty repeater - items not moveable, deletable or to clone
if ($field->name === 'products') {
$childPages = $page->children('limit=15');
$pagination = $childPages->renderPager(['getVars' => array("id" => $page_id)]);
foreach ($childPages as $childPage) {
//build the fake-repeater header
$wrap = $this->wire('modules')->get('InputfieldFieldset');
$wrap->addClass('InputfieldRepeaterItem InputfieldStateCollapsed InputfieldRepeaterMinItem InputfieldNoFocus');
$wrap->name = "repeater_item_{$childPage->id}";
$wrap->label = $childPage->index + 1 . ': ' . $childPage->product_title . ' Art.: ' . $childPage->title;
//if all fields are filled out mark the header
$isFilledOut = ($childPage->product_keyword && $childPage->product_type);
($isFilledOut ? $wrap->addClass("text-black", "headerClass") : "");
//add the edit button for the child page (class pw-modal for modal edit)
$submit = wire('modules')->get("InputfieldButton");
$submit->attr("value", "Produkt Details bearbeiten");
$submit->attr('data-href', wire('config')->urls->admin . "page/edit/?id=" . $childPage->id);
$submit->addClass('pw-modal uk-margin-bottom uk-margin-left');
$wrap->add($submit);
$form->add($wrap);
}
$field_style = '<style>.text-black{color:black !important;}.InputfieldRepeaterItemControls{display:none !important;}</style>';
$event->return = $form->render();
$event->return .= $field_style;
$event->return .= $pagination;
}
});