I want to merge 2 CMS using .NET. I want to know if it's possible to do it.
I want to use Kooboo and NopCommerce. Kooboo as the root CMS and NopCommerce will be used on a subdomain
Kooboo CMS has provision for extension modules (http://www.kooboo.com/docs/kooboo-cms/module_development_43). That means that if you would like to use Kooboo CMS as one of the building blocks of your solution then a 'module' is the most natural way for it to interact with another system.
I've not used NopCommerce before, but it looks to be a product designed for providing cataloguing and e-commerce capabilities (something which is not present in a default Kooboo CMS installation).
If your requirements are as simple as "kooboo cms with ecommerce support" then I'd suggest ignoring NopCommerce and instead look at Virto Commerce. That is similar product but already has compatibility developed http://www.kooboo.com/products/virtocommerce
Hope this helps.