create a sequence drag and drop activity converting to free-form?

Hi there,

I´m having trouble with a free-form activity. The idea is to drag different objects (pictures) to a table, this is a single drop hotspot, but you have to drag and drop all the objetcts in the right order, otherwise you will always do it right!. So, learners should have dragged and dropped object A before drag and drop object B. Then, they should have dragged and dropped correctly objects A and B to get C right and so on...

I´ve tried setting conditions, but it doesn´t seem to work and if you drop one object before the instruction you just skip some steps in the middle and get it right anyway...that´s not what I´m looking for... 

You may get a better idea if I describe the scenario: there´s a table and some people are ordering different dishes. All the dishes are available, not hidden, from the beginning but the characters ask to be served one dish at a time, and only THAT particular dish...once you´ve done it right you´re being asked to serve another one and so on....Every time you serve the right dish you receive a prize and a music sounds to give positive feedback, so there are many triggers involved...

Is there an optimal way of getting this??? it seems I´m taking detours and the largest way and I would be very grateful if anyone can points out some shortcuts to get this...

Thanks in advance. 

Laetitia