You could use the SmartLighting smartapp and create a rule there. You could use a routine to do it. You could go more advanced and use a virtual switch to group the three together. You could use 3rd party apps like webCoRE, Stringify and/or SmartRules, Yonami, etc. Seriously, the possibilities are endless!
For the “turn blue at sunset” scenario, I’d just go with a routine that sets all three to the same value (level and color) and have it automatically trigger at sunset and then turn off either at sunrise (or a specific time).
To group them together, I’d create a virtual switch (using SwitchMania is the EASEIST solution to this), and have all three on that virtual switch.
