Well I wouldnt have put all 3 into one pot in the first place, but there still young and cant have many roots so you may be able to remove each plant then like you say replant into some cups
Just take your time when doing it and try to do it asap... As the longer you leave it the more chance you have of the roots forming one root ball, then your never going to get them out with out cutting some roots and you dont want to have to do that