Man, I remember this sk back from 2020 when I had TAC case about, when smart-1 cloud was fairly new. Here is what TAC guy told me, he was super nice and helpful about it, see if this helps.
Andy
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--->To add address-range via API:
mgmt_cli add address-range --batch address-ranges_full.csv
#cat address-ranges_full.csv
name,ip-address-first,ip-address-last
range1,10.0.0.0,10.0.0.100
---> To add a network via API:
mgmt_cli add network --batch networks.csv
#cat networks.csv
name,subnet,subnet-mask
network1,10.10.10.0,255.255.255.0
network2,20.20.20.0,255.255.255.0
network3,30.30.30.0,255.255.255.0
---> To add a host
mgmt_cli add host --batch test.csv
#cat test.csv
name,ip-address
obj1,192.168.1.1
For more info, please refer the: https://sc1.checkpoint.com/documents/latest/APIs/index.html?#cli/add-host~v1.7%20