"How can we break down HR department silos?"

You may be getting ahead of everyone with this question. It assumes others agree that the problem even exists.

Think about engaging folks in a dialogue around "what gets in the way of higher levels of performance?" See if you can walk away with a prioritized list along with a few people who are willing to convene an initial scoping out discussion. Don't try top work the problem at this meeting. Rather, create the space where different voices can be heard. There may well be something going on you completely missed.

One caveat in all this siegert....our comments are at a distance. You know better than anyone else what is best for your community.