Steve knowing how strong character is Peter I of Castille I doubt a lot that Peter would accept cede Galicia to Portugal in excahnge of help, in OTL with a worse situation for him that in TTL Peter I never had accepted this kind of cession of an important region of Castille to Portugal.
Respect to Navarre well Catalonia is some far and very different that Navarre to think that Charles want annex this -because probably Navarre would be making too much overextension in a land that surely would rebels against Navarre-, a more realist and plaussible would be that Navarre annex the old counties of Sobrarbe and Ribagorza in Huesca that are controlled by Aragon in exhange of join to the war