Problem with Mini-Windows

HI, I have been trying to post this but to no avail.
I am trying to find a source to custom create windows–double-hung or casement–for the two “sidelights” here. I have given up trying to save those mullioned panels, they are starting to crack and we need the air (but screened) up there, it’s the only window in the room. I appreciate the help, in advance.