Edit: NOTE, I am the receiver of the texts.
So many people asking me to have my wife do something different on her end.
Beloved, she is on iPhone because she doesn’t want to do anything “weird.” She is texting from her phone number using her texting app. That’s what’s going to happen.
Now, why can’t I get iMessage on my android phone? If it’s just a messenger app why not make it available for Android?
I’d use it.
I fixed this, tell the grandmother, I’ll only send the pictures etc via signal.
Set it up for her, put it on the home screen.
The grandmother (my Mom) is probably the 2nd most tech-savy person in the chat. She has dug in on this on my sister’s side. It’s not a huge deal. I’ve accepted that I just need to wait till the defaults change. Any video I really care about I make her send straight to my wife.