8l90e tap shift mode in drive on silverado

[melition]

I have a 2016 silverado 8l90e swapped into another vehicle using the matching t87 tcm. I have the transmission working in every way i want except for tapshift/manual mode. On the camaro and corvette using bcm communication it will enter manual mode with a signal instead of a range selector change, but on the silverado i cannot get tapshift to work with drive selected. It does work as it should if i move the shifter to D5/sport/low position, but i bought a 4 position shifter for my swap .
Is there anyway i can get this to enter sport mode in drive without changing to a camaro or corvette tcm? tune doesn't seem to do much and i cant find any info if flashing a corvette or camaro os would fix this or brick my tcm.

thanks for the help!

[Tre-Cool]

not sure if the parameters are the same for the 8 speed but in the 6.

u go to transmission --- Shift general
change the range active to D4. change disabling the Up/Down Req option too. (this option might be worth testing)

[melition]

I ended up modifying the shifter to move into sport and it works as it should now. I tried everything but a write entire os flash!