NEC3 ECC: How is concurrent delay treated under NEC option D?

Hi Glenn, thanks for the reply. Just wondering which date is important for the order of the delays. For example, the Contractor has delays on the design, (as Subcont.) you realized the wrong design in Jan 2020, but you need this design by June 2020 on your programme. And you have a site delay which prevents you to start the design related works, this delay occured in March 2020. What would be your approach on this?