Indeed, i have the source code, so i can customize all nopCommerce; but i would not be able to easily upgrade my plateform.
In fact my need is to add a link in the variant page to an action of my plugin. is it not possible without modify the Nop, is it ?
No it is not possible to complete this task without modifying nopCommerce code, but small changes shouldn't be feared. If changes are done correctly it can be easy to remain upgrade resistant.