Need some Helps for compiling own armbian OS for A04

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Hi Guys :
I just got my DevTerm A04 (A brand new but second-hand) ,I love this small terminal ! I wish I can learn how to compile linux os by myself , I read the guide here

Create-DevTerm-A04-OS-image-from-scratch.

Everything going well until following step:

    after image done
    uncompress the
    linux-dtb-current-sunxi64_21.11.0-trunk_arm64.deb
    linux-image-current-sunxi64_21.11.0-trunk_arm64.deb
     and then combine all files ,all the postinst, preinst,prerm,postrm
    to be one devterm-kernel-current-cpi-a04.deb

After uncompress the two deb files ,I get two folders which contains two tar.xz files each
(control.tar.xz and data.tar.xz ) ,data.tar.xz are some folder and files like system file, I can combine they into a new data.tar.xz(no sweet, of course ).

BUT for the control.tar.xz, I have confused , both control.tar.xz from linux-dtb*.deb and linux-image*.deb are contains postinst, preinst prerm postrm such kind of files ,I have also check the difference of these files ,they not the same.

SO HERE is my question :
HOW CAN I combine these files ? WHAT kind of commands should I input ? these files will not covery by the other which has the same name ?

OR ,THE COMBINE means copy the content in one “postinst” file to another “postinst” file , so make them into ONE “postinst” file ,The other files doing like “postinst” file ?

Thanks for answering my question!
Best Regards!!!