My DIL asked to call me mum when she was going through a bad time. However, she always found this difficult, which I understood, so I suggested she call me by my first name, which she also found difficult!. No, she wanted to call me mum, but it still wouldn't come naturally. I would rather she called me by my christian name.
It's a difficult line to tread sometimes. I would still like to be called by my christian name as I feel it is more friendly, but I can't go through it all again! So now we are nanny and grandad which I am not particularly keen on.