I can help you with the inter-camera triggers in
Blue Iris if needed. My own PTZ shipped out for inspection, but the general theme is this:
1. aim the camera at the scenes where you'd expect the action to happen, and create & save a Preset for each scene
2. in the camera's Web interface, go to the Settings > Events, then go into Smart Motion Detection and add an IVS plan to each of your Presets.
3. go into Deep IVS, and in each Preset, add one or more rules, like an intrusion zone or tripwire.
4. in the camera's Web interface, go into the PTZ settings and set an Idle Motion to send it to your main scene's Preset after x minutes.
Now get into Blue Iris's Camera Settings for a spotter cam that would need to summon the PTZ when something happens. Like in my case, there's a shed that the PTZ would normally look away from. In Blue Iris, I can right-click the shed cam, choose Camera Settings, and then in Alerts I can hit the "On Alert..." button and add a "Do Command..." which issues an order to the PTZ cam to go to the Preset that looks at the shed.
Then the PTZ would swing around to the shed, where the new Preset contains a new Deep IVS intrusion zone and it ought to initiate auto-tracking from there. If nothing happens after x minutes, it ought to go back to its main Preset due to the Idle Motion task in the camera. Alternately, I can tell the shed camera to simply order the PTZ back to its primary Preset after the shed cam's alert expires due to inactivity.