Heirloom-shards exchange

Hi...i think A LOT of players share this problem with me,specially older players.

I got my heirloom in season 2(wraith) and i'm a caustic main.

I didn't get to choose and you guys added shards afterwards.

This is unfair towards player specially older players of the game.

Plz plz plz add heirloom-shards exchange but let it be usable only and only once so it won't be abused.