To configure more than one com-port you cant use the GUI !

You must use the vmx-file.
See my notes : http://sanbarrow.com/vmx/vmx-serial-ports.html

Please note that I wrote those instructions for Workstation 7.
When I wrote, that you can use up to 4 physical com-ports inside a VM, this applied to Workstation 4.5, 5.0, 5.5, 6.0, 6.5 and 7 only.

As far as I know versions later than 12.01 can use only one or two Com-ports and those ports MUST be real Com-ports.

Additional ports supplied by a USB´- serial ports card/ adapter worked in the mentioned old versions only.
AFAIK what you have in mind will not work at all with any of the recent versions - I assume that the documentation in case it still mentions up to 4 possible com-ports has just been copied over from the working good old versions and nobody ever checked if that part still applies nowadays.

Suggestion: forget about trying to assign com-ports to your VM.

Try to provide the com-ports by connecting a usb-2-comports adapter to the VM and set

serial0.present = "false"
serial1.present = "false"
serial2.present = "false"
serial3.present = "false"

in the vmx-file.

Ulli