schwim
Any way to receive group texts without RCS?
Yes, turn off RCS in the same menu where it says rcs connecting.
I'd deregister RCS here to be double sure:
https://messages.google.com/disable-chat
(So someone doesnt send you an rcs message and you never get it)
Any group chat of 2 or more people, you create a new group with everyone in it then send a message.
Have one person with RCS change the name of the old family group chat from "family" to "old family" or something. A clue to not use that group chat that has you not receiving RCS messages.
Any messages directly with one person will switch over fine.
It might take a little bit of time for other people's phones to realize you are SMS/MMS now and not rcs. Sending a text after all of this may speed up the process.
SMS/MMS lacks emoji reactions, higher quality photos, longer higher quality videos.
Maybe a messaging app like signal or threema would work for your family.
Your texting will work after all of the above.
Feel free to ask any questions or receive help here before it gets to a week of broken rcs.
Take care, sorry about your situation and rcs not working.