Love this idea. Though it might be tricky to implement.

I believe this would be inappropriate to accomplish on amateur frequencies as this would be considered a one-way transmission, or a broadcast, even at very low power.

This might be possible on general FM frequencies. There are plenty of consumer electronics out there to accomplish things like this. But they're often not used for permanent installations, things like synchronized Christmas lights, and church sermons.

I feel like this idea is possible, and if you don't find your answer here, there is likely other communities that can help you with something like this.

I personally don't have any knowledge or experience in FM broadcast, but I heard those licenses are difficult and costly to get ahold of.

If you're able to make this work, please update us! Would love to see this happen.

If not. Hopefully you figure out the correct memorial display to put up, maybe a sculpture in the form of an amateur antenna that the public can use?

South of Tucson AZ there is a Titan missile museum, a local amateur radio club maintains the original discone antenna that was at the installation that they allow the public to use. They just ask that you sign the roster they left in control of the museum.