Access restriction to files uploaded on a Board

[R Kh]

Is there a way that I can define access to an attachment on a card in a Trello list. I only want project sponsors to be able to access a specific document. If there is no way to do this maybe there is an add-on or plugin that is able to accomplish that task

(e.g.:
There is a task(card created) on a board for head of a team to calculate bonuses for board members for a project that is almost done. Ofc, I dont want all the members of this board to be able to have an ability to see/download this file, even if it is protected via password)

Any plans on doing that?

[marc -Collabello--Phase Locked-]

In Trello there is no direct method to do this.

However you can link to a file in e.g. Google Drive or Dropbox, and make this link only accessible to the head of the team.