The next step will be for us to file an I-485 application for a green card with USCIS. The father entered the country legally on an L-1 visa almost two decades ago, so he is eligible to adjust status without leaving the United States or needing an I-601 waiver of any kind.
Now that his immigration court case is terminated, we anticipate no further hurdles in obtaining his green card so he can stay in the US with his family.