How to remove atoms from MP4?

How to remove atoms from MP4?

I'm merging two mp4 files for video streaming. the problem is, the merged
file contains two atoms, 1 atom from each file and that is a problem when
it comes to streaming. the client needs to wait until the first atom loads
from file1, than when it's time to play second part from file2 client will
wait again for the atom to be loaded. when your atom is small you may not
notice this, but when you stream a large video, atom file could be 7-10mb.
How can I remove those two atoms from merged file and create a new one?
what i've tried:
ffmpeg -i file1.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts
intermediate1.ts
ffmpeg -i file2.mp4 -c copy -bsf:v h264_mp4toannexb -f mpegts
intermediate2.ts
ffmpeg -i "concat:intermediate1.ts|intermediate2.ts" -c copy -bsf:a
aac_adtstoasc m.file.mp4
MP4Box -add m.file.mp4 -isma mf.file.mp4
mv mf.file.mp4 m.file.mp4