DON'T WORRY PEOPLE!!
I've heard this from two head teachers of English (one of whom contacted the board of studies because so many students were stressed about mentioning two texts)
1. YOU WILL NOT BE DISADVANTAGED
2. They will mark you essay as a whole, and will examine both texts you have used.
The marking guidelines for this question state 'analyse, explain and assess the ways belonging are represented in a variety of texts.' It is a positive thing if you've chosen to do an additional text if it lifts your argument. (But if you managed to do one text in depth that is equally okay.)
ALSO
people who are worried about not addressing the 'celebrating relationships' part of the creative writing section- if your story looked at relationships falling apart and NOT celebrating relatioships that is equally okay- that sentence is just like visual or written stimulus you can go with it or against it. (again heard from HT of English.)
SO DO NOT WORRY !! Focus on paper 2 because you have NOT screwed up paper one.