Bungee 1.13 want 1.8-1.13 clients to connect

hey first post ever here as i usually sort out most of my problems or mistakes. but im quite confused.

i have bungee (1.13) and have 3 other servers which are

hub server: 1.13
Factions: 1.8
survival 1.13

how do i go about letting clients connect to bungee using any client from 1.8 to 1.13

if someone could help that would be great.