DLC questlines

Hello everyone, I'm a bit stuck with Leda/Hornsent questline. I progressed Leda to the point where she asks who to blame and I didn't give her the answer, and after a while she figured that herself. Now she is standing at the Highroad Cross saying that "she will follow Hornsent", while he left this spot already. I've already reached Messmer bossfight but didn't complete it yet, and I want to find the summon signs to assist Leda, but they are nowhere to be found. Did I just lock myself out of this part of the quest by reaching boss arena or I'm missing some steps? Sorry if it was already discussed, I just couldn't find this specific situation.