New C++ Class - Support UE3 packages possible?

I don’t want export ue3 project file and assets into current ue4 with that tool from github, I just asking if can write new Class for previous Unreal packages, without whole UE4 Source code. Thanks!

UE3 and UE4 content/code is not compatible.

Saying ’ not compatible’ you mean restricted?
But Epic already shared source code, so everyone is able to modify this engine for their own engine?
Seriously, any person known in C++ Language which working with Team can fully modify Unreal Engine for thier own Engine and promote this engine for thier game release?

I just asking.

You’re talking about supporting ‘UE3’ packages - so I assume you mean packages from Unreal Engine 3, or UDK. They are not compatible with UE4, they will not work or import. UDK also uses Unreal Script as a programming language not C++, they are fundamentally different.

Also, the rules regarding UDK/UE3 content are not the same as UE4 content. Check the FAQ for info.