Additional PXE options from ISO's ( other than official from GSS)

Hello, 

Is there a possibillity to add some other PXE Boot Menu Options - not those one like offial ones - like WinPE 3.1, 5 or 10. 

I mean - I have some ISO (normally I am using it as USB pendrive) with GRUB2 and Syslinux and I would like to add it as an PXE option. 

(for example this ISO is prepared as Multiboot silution with GRUB2 - also includes Ghost Configurations from Ghost Boot Creator) 

In attachment I've add screenshot with this possibillity , but I have no idea how I could achieve that.