I would also say that at least two of the Vanir are also tied to the Jotuns, as Freyr is tied to Gerda and Njord was married to and divorced from Skadi. While we know little about the husband of Freya besides the name Odr, this might be a name for Odin or a name for another deity entirely. But there is another Jotun who has her heart, in a matter of speaking, and that might be Loki. If Freya has the byname Gulveig, and if She was the one trapped in Odin's Hall at the outset of the war, it would have been Loki who ate her heart. So each Vanir deity is tied to the Jotun pantheon in very intimate ways, I would say.