@legs13,
If I made my own screen, would it still work with the functional window? I guess I'm interpreting your suggestion as a replacement frame....
Nah...just disregard the existing window frame. Don't try to attach the wire to it. The plastic will probably split & break if you try to drive a bunch of screws through it.
Just cut the new wire screen an inch or 2 or 3 bigger than the window. Lay the wire over the window and lay the new frame pieces over the wire and screw it down. It don't have to be the exact size or shape because you won't see it from the outside. You won't even have to buy the corner kit to attach the 4 pieces together (more money) Screw the long top & bottom pieces down like I described in Post 18. Then screw the 2 short ones on at the ends of the windows.
If that interfers with the operation of the window, and you can't figure out a workaround for that (maybe remove the inside latch and put a pull on the outside) Then you'll have to go to Plan B and install the screen on the outside.
Hope all that made sense.