I have a pool of IP 172.16.251.0/24 without NAT those IP source has access for a particular firewall. Currently I have a few users doing VPN with the following:

Customer1 Remote IP 172.16.251.2
Customer2 Remote IP 172.16.251.3
Customer3 Remote IP 172.16.251.4

Now I need to assign 172.16.251.5 with IP pool 172.16.0.0/24 with NAT to Customer4 but behind IP 172.16.251.5 for example.
Customer4-user1 Remote IP 172.16.0.2
Customer4-user2 Remote IP 172.16.0.3
Customer4-user1 Remote IP 172.16.0.2
Any help! Please!

Well, you create a new secret in PPP and in Local Address, set as 172.16.251.5. In Remote Address, set a pool 172.16.0.0/24.
After this, add a NAT rule in Firewall.

If understand your question, think that is this! If i wrong, sorry...

Sorry for my english too...

I try net map not work