Port Forwarding to Multiple Statics privates IP Addresses with 1 open port for all

I have a port forwarding question that I' m hoping a simple answer I' m trying to forward traffic and redirect it to a range of internal static ips ( 10.X.X.56 -10.X.X.76)  and all should have access to the same port YYYYY . I also want to be accessible from the outside from only 1 ip address.

In other words I' m trying to translate the same external public IP, with unique ports, to different internal IP addresses.

I have a fortigate200E.

Thank you fro any step to step