News posts states you are able to do this, I can't figure out how.
If you go to the user's profile page and have more than one kind of colour fireworks, you should see the option to launch them one at a time. The only time I found it didn't work was when a message came up to state that the user already had a firework of that same colour waiting to go off.
If a person has more than one color launched at them within the 15-minute time frame they last, the colors mix during that overlap period. 
You don't combine the items themselves, just the effects. And yes, it does mean that the colors can be launched by different people and still mix!
You don't combine the items themselves, just the effects. And yes, it does mean that the colors can be launched by different people and still mix!
Thank you both for replying. Apologies for not thanking sooner. Kind of forgot that I posted this.
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