EBU Single Rulebook Q&A 28 May 2014 2014_1253 Grandfathering of own funds instruments

Is buying back parts of an issued Tier 1 instrument that do not meet the requirements of Article 53 in Regulation (EU) No 575/2013 (CRR) but are eligible for grandfathering possible, or would it make the remaining outstanding amount disqualified for grandfathering? This question is similar to Question 2013_18, but keeps the contract of the instrument unchanged.