None of us know them, so what’s the difference?

I don't see what it matters as long as you're not using their last name.

Just make up a name if you don't want to use the real first name. I don't see what harm that could bring. It's a lot better than having to say all the time, "my sister-in-law". Just make up any old first name. However, when you're first writing about them, it seems like you would still have to say who these people are, in relationship to you, so I don't know how you avoid that.

I don't usually mention names on my posts but in DMs I will use their first name only.
I think using only first names on a post would be fine though.

The relationship is probably more helpful than the name, and people who bc wish to harass will use names to figure out who you are- I’d suggest not using names. Or make them up like “my sister Julie…”

They are already listening to you through your phone, they know where you live, where you bank, where you work, how much money you have and every website you ever visited. They don't need a reminder of what your wife's name really is since they have all the goods on her too.
Still, use a different name.

I only use my family's real names in PM's/

No... don't do that! Exposing someone else's identity unless they hold public office without their express agreement is unethical.
If you can wrap your head around it, use a made-up name.... it matters to nobody else what silly name you call the person - or yourself

Why not

You just killed the post where you said she is Mrs. Hyde, then defended her.

Figure this out on your own.

But def do NOT use their real ANYthings.

The less personal in any chat room the better for them and you

Use first names no last names no photos ever. If you use fake name you will have to remember all the fake names.

Some people just use the first letter of their name. I have done that before.

Make a fake name it's better