Ok, I did that and here are the results.
After changing to Safe Mode and creating a group text using Messages+, my recipients did receive the group text, but the text came from the (588) area code number I listed before and it said:
MYCELL# created a 'Test' group with you.
RECIPIENTS CELL # +1. Reply to chat or type #help for tool tips!
Tap on the avatar to add this group to your contacts.
Then my actual text showed below it:
MYCELL#: Let me know what you get.....
My son replied to the group text, and I received it in Messages+ application only. I switched to the default Messages app for Android while in Safe mode, the reply to the group, or my text to the group was not in the list.
See the Screen Shots. The first one is from my son that uses "Textra" messaging app, the second one is my Messages+ app, and the 3rd is my default Android Messages app where you can see there is no group message displayed in the default app. It only shows up in Messages+.
Screen Shot from my son's Textra application showing he received the message, but from a different number:
My Messages+ application from where I sent the text and he responded:
Default Android Messages app, no group text, just the individual texts I sent letting them know I was sending a test group message.