Hi Kamishiro_Takuto
I don“t know how to create automatically the entry in the second list. (I think this trouble you have to solve with VB or C# code)
To do the retrieve, You have to create a new conection data for retrieve and set your second list and the colum ID for the retrieve. The second you have to do is create in your first form a Text Box and add a Action Rule. This action will be "Set value field" the you select the field and press FX btn and Select the Colum ID from the retrieve ID. If you want to the the lastest ID put a Xpath formula like this:
xdMath:Max(xdXDocument:GetDOM("retrievelIDs")/dfs:myFields/dfs:dataFields/d:SharePointListItem_RW/d:ID)
Regards
jricorod