Hi @cecilehabran , thank you for considering my plugin.
‘Each domain a page’ serves from the one WordPress install it is a part of, every address that reaches your WordPress installation can be picked up. In this case, your slug should be offer-2-example-com (including the domain, it does not matter that this is the same domain as your main website).
The only slug that does not work is the exact domain your blog is sitting at (in your case would be offer-example-com) because ‘offer.example.com’ will serve the homepage and my plugin will not do anything.
Let me know if this works. If it does not, I will investigate.
Kind regards,
Joeri
Marking this as resolved as it should work and therefore I consider it working until I hear otherwise.