N1MM SO2R with Two Physical Flex Radios (8600 + 6400) - Looking for Guidance

N1MM SO2R with Two Physical Flex Radios (8600 + 6400) - Looking for Guidance

I have the whole SO2R stack: tuner, antenna, and power geniuses.

I'm trying to configure N1MM Logger+ for the upcoming ARRL VHF Contest using:
Flex 8600 (192.168.2.10)
2m / 222 / 432 / 1296 through a Q5 transverter
Flex 6400 "LilBoy" (192.168.2.20)
6m FT8
SmartSDR 4.2.20 on both radios
SmartCAT 4.2.20
Both radios running simultaneously on the same PC
My goal is:
Radio A = 8600
Radio B = 6400
N1MM SO2R
Single N2LQH contest log
I can run both radios simultaneously in SmartSDR without issue; the challenge is getting N1MM to recognize them as two independent radios

What I initially tried
Created two SmartCAT COM ports:
COM14
COM17
Configured N1MM:
Radio 1 = COM14, FLEX-6000 Series
Radio 2 = COM17, FLEX-6000 Series
Problem
Both N1MM Entry Windows always show the same frequency.
Further testing revealed:
COM14 follows whichever radio currently has focus in SmartCAT.
COM17 also follows whichever radio currently has focus in SmartCAT.
In other words, they are not independently tracking the 8600 and 6400.
Additional testing
Created dedicated TCP CAT ports:
8600
TCP CAT Port = 8600
6400
TCP CAT Port = 6000
Configured N1MM as:
Radio 1:
TCP
192.168.2.10:8600
Radio 2:
TCP
192.168.2.20:6000
Result:
N1MM shows "Manual Radio"
No frequency updates
CAT communication appears not to work
Other observations
When using COM ports:
N1MM does communicate with the radios
But both CAT ports track the active radio rather than separate radios
When using TCP:
N1MM does not appear to communicate with either radio
Questions
Has anyone successfully configured N1MM SO2R with two separate Flex radios (8600 + 6400) on the same PC?
Is this supported in SmartSDR 4.2.20?
Should I be using:
FLEX-6000 Series driver?
Kenwood emulation?
N1MM Spectrum/N1MMLib integration?
Is there a way to create CAT ports that are permanently bound to a specific radio rather than following the currently selected radio in SmartCAT?
Is this only supported in SmartSDR v5 or later?
Any screenshots of a working dual-Flex N1MM configuration would be greatly appreciated.
73,
Terry N2LQH