I have a rules question for Changeling: the Lost. We're coming to the end of a year long story arc and one of my players is very interested in the dual kith stuff from Winter Masques. I'm tempted to let her have it as suitable reward for what's going on in the plot, but...
How would you rule the use of the dual kith merit when the kiths of interest are from different seemings?

The character in question is currently a Darkling Gravewright who works as a bartender and the player would like to use the dual kith merit to pick up the Wizened kith of Brewer.

Would it make sense for the second kith to only give the kith blessing or would it make sense to open up all of the Wizened stuff including the reduced cost for Artifice contracts with the second kith? Winter Masques is somewhat unclear- all examples they give are of two kiths from the same seeming. Opinions?

Thank you