Schreiben von Software

I've purchased an Magento-Script called "Airhotels" two years before. I installed it as a rental booking platform for unusual accommodations, connecting people looking for unusual stays. Owner can list their unusual properties on customer backend. Now I need for some properties when set to "out of stock" an link to static CMS-site (but for each out-of-stock-property their own). The forwarding should preferably run over the existing "Book now"-Button (see attached Screenshot), only with other label text. Calendarfunction in the pricebox should be hidden (only if property is set to "out of stock". For your understanding: I need this forwarding to link some properties with a customized bookingform of an affliliate-partner that will be embeded per iframe on the respective cms site. Please ask if something is unclear!