I really feel you on this, moving and changing schools at the same time can be so tough on the little ones. You might want to try posting in the Marine Parade or Pasir Ris family Facebook groups to find other parents doing a similar route who might be open to sharing a private transport arrangement. Some schools also have their own school bus vendors who can do custom routes, so it is worth checking directly with the preschool admin if they can recommend anyone lah.