my elder dd is desperate to share her room with her younger sister (16 months). but that means dd 2 moving in to bottom bunk. and it means i can make nursery an office. is 16 mnths too young to go into proper bed? even with a rail? also do i keep her in a gro bag in the hope of containing her or bite the bullet and give her a duvet? or shall i just wait a few months? thanks.