Yes that is also my experience - that if possible it is nicest to add the relation first and then sort out all "level" stuff. 

Seems like we are no a similar mission:-) I have added relations to make it easier to visualize the rivers. Like https://sv.wikipedia.org/wiki/Hove_%C3%85 for just Hove Å and https://sv.wikipedia.org/wiki/Lista_%C3%B6ver_vattendrag_i_Danmark for the 15 longest rivers in Denmark.