1- reboot in recovery and flash the new TWRP with Multirom support; --> HERE 2- reboot the recovery; 3- flash the kernel with the kexec hardboot patch ( it's my chupakernel 20D based, might works well also with the 20E roms) 2Gb/16 HERE and 3Gb/32 HERE 4- flash the multirom zip; ---> HERE 5- install every Rom you want ( advanced--> multirom --> add rom ) 6- reboot and choose the rom you want to boot.
Thank's to Skin1980 to developed , find the tread on xdaHERE