Hi @Anonymous
I'm not sure I understand. Your users can select an Item in a dropdownlist (from List A), then go to another screen with an edit form and you want to display an item from List B with a specific ID. How do you know which ID ? From the dropdown plugged in list A?
On your EditForm control, you can set the Item property to :
LookUp(ListB, ID=0) //Replace 0 by the ID of the Item you want to retrieve
If the ID is a property of List A, then you can do :
LookUp(ListB, ID=DropDownListA.Selected.IDListB) //Where IDListB is a number column of ListA that stores ID from List B
If this is not what you're looking for, please explain us a bit more.
Théo