Include fallback to my collection

So I have created a simple related articles collection, that will get all pages within the same ‘category’ excluding itself.

$related = page('blog')->children()->listed()->filterBy('category', $page->category(), ',');
$collection = $related->not($page->uri());

I want to add in a fallback to this so that if less than x pages have the same category, then fill up the remaining x with the latest articles.

So if i’ve set a limit of 4 related articles, and only 1 page has category of ‘web’, then fill the remaining 3 with latest articles.

Can someone point me in the right direction please? I’m guessing it’s an and/or type filterby statement?

That would be something like this:

$count = $collection->count();
if ($count < 4) {
  $limit = 4 - $count;
  $latestArticles = page('blog')->articles()->sortBy('date', 'desc')->not($collection)->limit($limit);
  $collection = $collection->add($latestArticles);

Thank you very much.

I ended up with

    $related = page('blog')->children()->listed()->filterBy('category', $page->category(), ',');
    $sorted = $related->sortBy('noteDate', 'desc', 'noteTime', 'desc')->not($page->uri())->limit(2);

    $count = $sorted->count();

    if ($count <= 2) {
        $latest = page('blog')->children()->listed()->not($sorted);
        $sortlatest = $latest->sortBy('noteDate', 'desc', 'noteTime', 'desc');
        $sorted = $sorted->add($sortlatest)->not($page->uri())->limit(2);

Which seems to work as expected. Thanks for the help.