Are the commas optional?

Could someone please help? Thanks.

I just don't know.

Grammar is not set in stone. There are two approaches to grammar, prescriptive and descriptive.

Prescriptive assumes there is only one right way, whilst descriptive looks at how people actually talk.

Prescriptive the commas are not optional.

Descriptive they are.

Decide for yourself which ideology you subscribe to. That should answer all your questions.

My elder sister, Eve, is hardworking.

Without any commas, the sentence says that your older sister is hardworking.
With both commas the sentence is ambiguous.
I.e. the sentence could mean that you are telling someone called Eve that your elder sister is hardworking.

Excellent.

Didn't we just do this with a clever brother?

No, this is the older thread.

The OP has a habit of asking the same question over and over again.

Yes, I've noticed that and have stopped providing the same answers. He really should study the article on the use of commas I've provided to him several times before he asks the same old questions.

Thanks, Morgan.