From picklist to multi-select combo box

[geraldbigot]

Hello,

I need to transfer values from several picklist to one multi-select combo box, with workflow I hope.

My question is :
After first value transfer (from first picklist), could the other value (from second picklist) add to first one or they would replace it ?

For example :

We have 2 picklists :
First one with A, B and C values
Second one with D, E and F values

Multi-select box have A, B, C, D, E and F values

First I transfer the value A of first picklist : so combo box is like that : A selected
If I transfer the value E to combo box : could I have A and E selected or E replace A ?

I hope to be clear enough.

Thank's for help