I am doing exactly the same Lixatron as I went back to conduct an ethnography in a school I used to teach in. As mine is narrative, reflexivity run right through it. I have used a reflexive diary and illustrated the methodology with critical incidents and other extracts from the diary. I have a whole section outlining my previous role and relationship with the participants. Not sure whether it will go in at the beginning of the methodology, or in a different part at the end.