Firmware request: 7i96s with modbus/PktUART and 7i85 daughercard

Hello,
I think I need custom firmware/bit-files for my setup.
I have a 7i96s with 7i85 db25 daughter-card, which in turn has 4 encoders, a 7i84u and a 7i73 attached. I want to control my Invertek ODE-3 spindle vfd with modbus from rs485 on the 7i96s. 

Unless I'm mistaken, the standard 7i96s_7i85d files don't feature PktUART for modbus on the 7i96s. Everything else seems to be working with them. 

It's a 4 axis mill, so if possible, I also wish to retain the encoder input on the 7i96s for a spindle encoder - (if i understand correctly there can be complications there due to muxed vs unmuxed?).

I've had a look for existing firmware, but don't notice a suitable option in the standard 7i96s package. 
I also read the below linked thread, but don't see links for bit/pin files there.
www.forum.linuxcnc.org/27-driver-boards/...dbus-pkt-pin?start=0

Would this be possible please? Any other information needed?

7I96S  + 7I85 with PktUART on 7I96S RS-485 interface

Note that sserial channel numbering on the 7I85 has changed
since old sserial channel 0 on the 7I96S has been replaced by
a PktUART, so sserial channels 0..4 instead of 1..5 are on the 7I85.

Encoder on the 7I96S is encoder 4  (same as normal 7I96S+7I85 configuration)


 

Thank you! Mesa customer service is outstanding.