Advice please

Hi – I would be extremely grateful if you could assist me. My sister died a few years ago and we are trying to sort out her gravestone. Her grammar was excellent so she would be very annoyed if I got it wrong. I am in dispute with her partner over the statement below. The first one is what I have written and the second what her partner wants. I have excluded names just in case...so hope that’s ok. My sister was not the biological mother, her partner was, but she certainly was their mum. Although very young when she died they knew she was their mother. Anyway I would be grateful for your views.

1. Beloved daughter of *** and ***, devoted sister of *** and *** and treasured Aunt of ***.

Loving Civil Partner of ***, adoring mum to *** and ***.

However her partner wants the following

2. Beloved daughter of *** and ***, devoted sister of *** and *** and treasured Aunt of ***.

Loving Civil Partner of *** and adoring mum to their children *** and ***.

As you may have gathered my grammar is not very good, but as I see it there is only my sister in the grave so the statement should be singular rather that plural as I believe it is in the second. If her partner was buried also then the phrase ‘their’ would be appropriate.

Anyway, I would be extremely grateful for any suggestions on what is written, the style or the language used. My sister would want it correct – especially on her gravestone and I wouldn’t forgive myself if I got it wrong, so want to ensure it is.

Take care & many thanks