Portuguez,
Could you clarify this section:
"... once there, they have different vpn connections to our customers. We need a solution where the connections to our customers uses IP addresses from our main office."?
If consultants are working from home(remotely), and they're using client VPN into the main office then they'll be the configured subnet. If they are directly connected to the customers network, and they VPN into the main office, it would be the same subnet.
If consultants are connecting to the customers network via another VPN, you cannot VPN from that endpoint back to the main office as there would be erratic routing issues.
Cheers,
Nick