The non-resident (and non-local) parent should have the children this weekend but has been prevented from doing so by the bad weather. The resident parent has plans for an important family celebration next week and they can't be moved to this weekend due to the weather and old age/ill health of one of the family members which means they can't walk to the venue (4 miles away) in the snow. They also have a photographer booked for the celebration.
The non-resident parent is insisting that the plans be moved to this weekend or cancelled.
Who is being unreasonable?