Hi,
Let me address your inquiries one by one:
1) How to change IP of VPS after provision.
Either your client should modify the number of IP addresses under configurable options and pay the invoice, or you can run the "Change Package" command in the admin area.
Before i could delete the ip and add one manually. Now the new ip not returning to pool (when terminating product) if the ip is manually added to product.
The IP addresses added directly on the hosting page are not returned to the pool. Please add the IP address before creating an account to the pool in the Proxmox Addon or
IP Manager For WHMCS.
2) How to add missing IP back to IP pool, as it accepts only as subnet. if i add entire subnet its duplicating ips which are active with products.
It would be best if you
get in direct contact with our Support Specialists so they can have a further look at the encountered issues.