I write group_members, but recently had to write a report that was based on all the team members of all the teams that someone belonged to.
I was going to write this, but it seems the guy who did our ServiceNOW initial implementation wrote an Include that did this for me. It was not available for me to use in a report, but again, making this into a business Rule works
I have modified it a little by ensuring that a name appears in the return value just once.
can change it if you want ID, but for the reports name is a better option
Name - get_TeamMates
table - global