FFmpeg - Convert filter_complex to filter_complex_script

Question

I would like to add a large number of pictures to the video using FFmpeg, but the maximum length of the string for the command prompt is 8191, so I want to use filter_complex_script instead of filter_complex.

How do I convert filter_complex to filter_complex_script, and how do I write the names of the files and options in the text files?

command line:

ffmpeg -i input.mp4 -i a.png -i b.png -i c.png -filter_complex "overlay=0:0:enable=between(t\,1\,2),overlay=0:0:enable=between(t\,3\,4),overlay=0:0:enable=between(t\,5\,6)" output.mp4

How do I include file names? I used this command:

ffmpeg -i input.mp4 -i "files.txt" -filter_complex_script "myscript.txt" -c:v libx264 output.mp4

But the file names appear as a black rectangle.