Co-habiting advice needed

As complicated as it might be, it can still be described and written down. There's no required format so if it needs diagrams to help explain then use them too!

Co-habitees have no standing in these cases as much as they may like to think there is. It's next of kin that matters unless defined in a will. My friend got hit like this some years ago where he had been very happily living with his partner for many years and then she suddenly died. He was left homeless as everything went to the partners family and they turfed him away.

There is no way on earth I would ever leave everything to one member of the family and let them sort it out between themselves! The arguments, discord and heartbreak created in that instance would be awful. Obviously different families have different dynamics though