denon receivers and harmony

OK, just finished the basement. Using Denon 3808 for 7.1 in main "family room" downstairs. Also have a gym and patio wired for speakers. My intent is to use my older 3803 as an amp. I have zone-2 pre-outs from 3808 into front speakers of 33803. That will power the gym speakers And zone 3 pre4-outs going to surrounds on the 3803 which will power the patio.

I am using a Harmony 900 remote for the setup.

Here's the issue I've run into: Since both receivers are Denon the codes are pretty much the same so both receivers respond to the same command.

Originally, I thought I might get around this by covering the I/R of the 3803 and using the Trigger Out on the 3808 to power on the 3803. I could then do everything on the 3808 zone commands. BUT, doesn't appear the 3803 has any type of "trigger in"

A little research dug up the "remote ID" function on the 3808 (something the 3803 doesn't have). That seems like a decent option but I can't find out how to make the Harmony send remote id 2 signals.

I'd hate to have to buy amps for the gym/patio when I already have the 3803 which has the amps I need.

Any thoughts?

Thanks. I guess that is worst case scenario. If I go that route that means I change the 3808 to remote 2 itself. So, can't use the secondary remote for it and I also have to program every key into the harmony.

At least it's an option, but one I hope to avoid if I can.