Outgoing ports rule

Hello:
Simple Question, I have a client that is a library that there software connects out to library consortium 's ip of 21x.x.x.x
they upgraded there software which runs on java, and the new software now uses new ports of 64000, 63100, and 63000.
I can see connections for three computers, under firewall/connections, once more than three computers connect in, I can see the 64000 port for those comptuers connection sittting at “time-wait” or queued,

What is the proper way or srcnat/passthrough to allow those 3 ports to bypass the firewall. The old software used different ports and allowed for 10 computers to connect at a time.

thanks
Quentin