Substitution parts visibility for a period

Hi

my supplier is unable to supply part. X till a date D1. I want enable substitute part Y for this part X in material master or BOM till date D1. I want yo see demand visibility of X in MD04 to be replaced by Y till date D1. Backflush also should happen with Y till date D1.

After date D1, Part X again become main part. How to achieve this ?