Yeelight - How to set colour to flash?

I am fairly new to the Xiaomi brand of smart home products but so far pretty impressed.

I currently have:

Aqara Motion Sensor
Water leak sensor
x2 Yeelight colour bulbs
Smart switch (round - 3 clicks)

Have more items on the way.

How can i set up so:

If Sensor in kitchen detects movement between 10pm>6am , then the gateway alarm triggers siren/light and the light in hallway flashes red?

I current have a scene so if i long press my switch the alarm activates the sensor in the kitchen, that works fine.
When i go into the gateway setting > Auto > Alert > Alert Trigger Condition
It only lets me toggle ‘Sensor’ on and off, does not let me select which sensor?

Many thanks.