((So Harry has sung IICF a handful of times on his 17/18 tour so far, and he has reportedly (from what i have seen and heard about his performances) done the same thing during IICF as he did in SOML))
He's sung the parts of himself and the other boys in SOML, all except for Louis. He let the crowd sing louis' part.
(Credit to @lookingforagloe in the comments for prompting me to edit this chapter.)
Harry allegedly shouted "I miss you!" After louis' solo in IICF, but this apparently happened in 2017 when he was performing SOML. It has been debated on whether or not it was after Zayn's solo all along, but people seem to think it was louis' solo.
Even if he didn't say "i miss you," @lookingforagloe informed me that during many concerts he paused before louis' solo and tried to calm the crowd down so they could focus on this part of the song, along with harry supposedly taking a 28 second pause before louis' solo.
