Thanks - to be clear, would that be the second scene with Patricia activated at this part of the industrial area?
To progress, after going to the next screen, you'll move to an intersection; the last Meleuma scene is in the area seen after going left, the last Greenhouse scene is in the area after going down.
After doing that, you should be able to access the last optional scene by going back to those three places in the industrial area.
After that's done, you use the flares automatically by progressing past this bridge area - if you haven't done all the optional chimera scenes when you get there, you'll be notified.
I hope that helped, please ask if you have further questions.