Thanks for the reply.
Here is what I have done until now.
Migrated the primary HA member (migrate export with R80.30 tools) to R80.30 on my VM.
Did another Migrate export on new R80.30 and followed the process in below article to separate the firewall. I have now the backup which should be able to migrate to a Management only R80.30. this seem to be easier rather than following a long process on R77.
Re: How to migrate from standalone configuration (... - Check Point CheckMates
I was building another R80.30 Management only instance in my lab to move this new Migrate export , but i had disk space issues in my lab which i am sorting now.
will update if the changeover worked and if the the script from infinity portal was successful.
do not think working with Primary member only will create any issues, rather than replicating the whole topology.
Thanks for your help @Anat_Eytan-Davi and @PhoneBoy