When did Lockhart Gardiner become Chumhum's firm? Did I miss an episode?

In the episode 4x13 "the Seven ngày Rule" L&G helped with a prenup and they gain the wife as a client. She has Chumhum actions, so she owns part of the company. In later episode they mentioned that they were trying to get all Chumhum.
But I don't know exactly when.