First of all, sorry for my bad english, I will try my best.
I have two API's using the same database, in theory for distinct purposes, one for the user (edit profile, get user info...) and another for finance (store a payment, store an order...). I have a problem with this architecture, because I don't know what I do when I make a function that I need in both API's, but only one have it, if I perform a request and set a cors protection or if I duplicate the code... Any suggestions are welcomed, but keep in mind that I cannot change the architecture.