I used the feature "Arrange > Insert > Advanced > CSV" and I am struggling to achieve the second point.
I already tried:
2 rectangles can share X links: I used the ("from": source column, "to": target column) with Target column ="id1, id2, id3". It works !
Each link has its own label: I created a column "Label". I used ("fromlabel": "label"). The problem is that the 3 links have the same label even if I put "label1, label2, label3" in the label column.