What particularly prevents your from using WinSCP with GPL license?
If you read the GPL License here: https://www.gnu.org/licenses/gpl.html
And look at the very bottom of the license. It says
The GNU General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License.
Thus, this prevents us from using the software as a component of our overall software solution, which is proprietary software. Furthermore, if you read the Lesser GPL license, it basically says that you can use it in a proprietary product if you acknowledge the product somewhere in your software, such as the About box if it is a user program. For another perspective on this, see: https://fosswire.com/post/2007/04/the-differences-between-the-gpl-lgpl-and-the-bsd/
This is why I am asking that the license be changed to a LGPL license. I am running out of time for this. I will give it a few more days, then I will have to find another solution.