You might want to touch base with Lippert Industries. They own Kinrow windows and most other window brands that are installed in RV's from all manufacturers including Keystone. Their website is:
http://www.lci1.com/support-windows for customer service on windows. It's possible that Lippert has the screens you want in their "online store". At their website, if you click on the "contact" button, it will open a screen with Lippert's phone, email and physical address. You can choose how you want to contact them.
Good Luck, and if you do find they have what you need, please post the information here for other members.