first of all: does he have kids with him? !!!

alaska has jurisdiction over the marriage, but if she moved to WA w/his and her kids.. and it has been 8 months the Uniform Child Custody Jurisdiction and Enforcement Act which the various states have consented to... may hold that for purposes of custoyd and support WA courts are the best place to make the determination.  otherwise i'd say file now in alaska (i would need more info for a full or really good opinion) but should not be aproblem... now.. here is the fun stuff....

you are going to have to file a number of paternity actions b/c their are two kids by him within the context of his marriage to her.. you actually may not have to file one re the child you conceived with him but the kid from the other guy with his wife here in WA is "born during the marriage" and thus he is the "the presumptive father until such is rebutted" by " clear and convincing evidence" like....like ... a $350 bucul swab dna test... bucul is a wierd word but you basically just swab dad and the kiddies saliva and test it... it will tell you for sure... the paternity on the new kid should be done down here b/c her new boyfriend needs to be named inthe court docs as one who must take a test also...