Shell Programming and Scripting

Hi, I receive a file that has Master record followed by one/more Child Records as shown below & also as attached in the file.

Now , The key for the child record is from pos 4 to position 80 in the parent record, now the requirement is to create two files
1. Parent file --> has all the parent records
2. Child file --> Has the key from the parent + Remarks i.e RMK TEST LINE 1 etc

can someone please help immediately?

ALT 00623047371 20120213021520120320195216PADVN2012032015520003543ATL
RMK TEST LINE 1
ALT 00623047371 20120213021520120320195246PADVR2012032015520003543ATL
RMK TEST LINE 1
RMK TEST LINE 2
ALT 00623053520 20120306041920120320195927PADRY2012032015590003543ATL
RMK THIS IS A TEST FOR CODE RED LINE 1
RMK THIS IS A TEST FOR CODE RED LINE 2
RMK THIS IS A TEST FOR CODE RED LINE 3
RMK THIS IS A TEST FOR CODE RED LINE 4
RMK THIS IS A TEST FOR CODE RED LINE 5
RMK THIS IS A TEST FOR CODE RED LINE 6
RMK THIS IS A TEST FOR CODE RED LINE 7
RMK THIS IS A TEST FOR CODE RED LINE 8
RMK THIS IS A TEST FOR CODE RED LINE 9

Output should be

Parent file or altparent.txt
ALT 00623047371 20120213021520120320195216PADVN2012032015520003543ATL
ALT 00623047371 20120213021520120320195246PADVR2012032015520003543ATL
ALT 00623053520 20120306041920120320195927PADRY2012032015590003543ATL

Child file or atlchild.txt --> should be a fixed width file having padded with spaces if required at the end.
RMK 00623047371 20120213021520120320195216TEST LINE 1
RMK 00623047371 20120213021520120320195246TEST LINE 1
RMK 00623047371 20120213021520120320195246TEST LINE 2
RMK 00623053520 20120306041920120320195927THIS IS A TEST FOR CODE RED LINE 1
RMK 00623053520 20120306041920120320195927THIS IS A TEST FOR CODE RED LINE 2
RMK 00623053520 20120306041920120320195927THIS IS A TEST FOR CODE RED LINE 3
RMK 00623053520 20120306041920120320195927THIS IS A TEST FOR CODE RED LINE 4
RMK 00623053520 20120306041920120320195927THIS IS A TEST FOR CODE RED LINE 5
RMK 00623053520 20120306041920120320195927THIS IS A TEST FOR CODE RED LINE 6
RMK 00623053520 20120306041920120320195927THIS IS A TEST FOR CODE RED LINE 7
RMK 00623053520 20120306041920120320195927THIS IS A TEST FOR CODE RED LINE 8
RMK 00623053520 20120306041920120320195927THIS IS A TEST FOR CODE RED LINE 9

Please show the output you want for this input.

Also, your attachment doesn't appear to have worked.

[edit] Attachments appear to be working again.