I like
Diederick, but I'm leaning towards the
Diederik spelling which is apparently also Dutch.
Arend
Vincent is nice, but I'd have to spend some time getting used to Arend.
Diederick Bram is pretty good.
Diederick Vincent doesn't flow that well imo.
Other Dutch combos:
Diederick FransDiederick Lieven (my favorite Dutch name)
Diederick NielsArend
GustaafArend
Jochen