I assume you mean the dialogs that are loaded upon kamailio restart, otherwise kamailio is using the records kept in memory and uses those ones.
Initially the dialog module was not designed to share the database table with another instance, but of course, a contribution can be made for this. Some similar work was done in the commit 506672e523a48985f89e2c35bdab3d024df0a34d, maybe you can look at it and come up with a PR for this feature request.