There's a special trick you need to know about if you want to email ALL CLIENTS that are traveling on the same group trip.

You need to manually check this box under 'EDIT TRAVELERS' within each trip:

If this is NOT selected in each trip,  an email sent from the GROUP level will only be sent to the PRIMARY traveler within each trip.

I'm copying the TJ Help Library steps for this so you don't forget this important step:

Article 1: https://help.traveljoy.com/hc/en-us/articles/360039644632-Automatically-copy-all-travelers-on-a-trip-when-sending-trip-messages