"We've been forging this friendship for over 25 years together… through this shared journey," the actress tells PEOPLE

The “Bridget Jones” franchise is long beloved by fans, due in extremely large part to Renée Zellweger’s portrayal of the title character. So, yes, the actress was a resource director Michael Morris turned to a lot while making the fourth film — and there was one particular insight from the Oscar winner that he says unlocked the whole thing.