Alright, so after searching around for more than a month, and going back and forth with Woocommerce's support team (they were no help :/ ), I came up with this solution:
Swimming around in the database I noticed that all memberships are just posts, and they have an ID and a post author. so I figured I could write up a little SQL to make it work.
using WordPres's built-in $wpdb class I was able to just update the field directly in the database:
first you have to include $wpdb in your function:
global $wpdb;
then you put the query together, below is what it looks like in regular SQL
UPDATE ie_posts
SET post_status ='wcm-active'
WHERE post_parent = 49 AND post_author = 49870
And here's what is looks like using the class:
$wpdb->update('ie_posts',
array('post_status' => $_status),
array('post_parent' => $_membership_id,
'post_author' => $_user_id)
);
I would advise trying this using a development copy of your database so you don't break anything.
deff not the prettiest way of doing it, but it works like a charm. if anyone has a better way of taking care of it, please let me know.