I can't send or receive messages in groups that include non-iPhone users

On my phone I can create a texting group by adding the users, and then will see and receive and send group messages on my phone, while the iMessage on my ipad doesn't see those, so perhaps to into the imessage on your phone, add each person individually to the group (as in just keep adding your recipients) and see if it works.

And you guys can always look for a third party app for everyone to use to message. I don't have one to recommend but that is another work around.