How to create a bootloader with three partitions [FreeBSD, Kali linux, WinPE]???

Question

Loaders

For those who are inattentive: with Sections and not images !!!

Answer 1

take and create. Take a bootloader, take system images, configure booting from them. To set up the boot, you will have to read the documentation and study how the systems themselves boot.
If you are too lazy to study, you can try YUMI, the program configures the bootloader on flash drives to boot from various images.