I get stuck when I have to put x1/ xprv code on Mnemonic Code Converter. It shows "Invalid root Key". Tried it couple of times, with and without commas etc.
https://ibb.co/cBiv76

In "BIP32 Root Key" box paste the x1 /xprv from BTG.txt we created, select “BIP32” and in Client select “Custom derivation path”, in “BIP32 Derivation Path” leave “m/0”

WHAT TO DO WITH CHANGE ADDRESSES:
Ok I said that this was only for “Change” addresses, let’s discuss about “Change” addresses (https://i.imgur.com/aZ7XHJd.png):

There is only one simple thing that changes:
In the step where we paste the x1 /xprv and the x2 /xprv code in iancoleman website you need to select “m/1” instead of “m/0” in “BIP32 Derivation Path”.
That’s it.