Complex sentence: Prior to the lawsuit, Warner/Chappell had been earning $2 million a year licensing rights to the song for commercial use, and further proceedings in the case will determine whether Warner/Chappell will have to pay back some portion of those licensing fees.
Split into simpler sentences: Prior to the lawsuit, Warner/Chappell had been earning $2 million a year licensing the song for commercial use. Further proceedings in the case will determine whether Warner/Chappell will have to pay back some portion of those licensing fees.