Just thinking really..anything could happen at any time. I hope it doesn't but you never know.
My kids have different fathers, dd doesn't see hers (long story), she doesn't know him really, they only had contact for about six months when she was five and nothing since. Ds has always had contact with his dad.
If anything happened to me I would want them to stay together, so I guess they would have to live with my mum. What rights would my exes have though? Would this be possible? Dd's dad wouldn't want her anyway, ds's dad probably would want him.