Danilov handed a jacket to the theater’s wardrobe

Danilov handed a jacket to the theater’s wardrobe

Danilov handed a jacket into the theater’s wardrobe, which was stolen by unknown persons during the performance. Danilov sued the theater to recover the cost of a jacket. The representative of the theater filed a motion to attract the participation of a cloakroom worker who was careless in her duties. Danilov objected to the satisfaction of the motion, believing that the cloakroom attendant should act as a witness.
As whom should the cloakroom attendants be involved in the proceedings?
Will the solution to the problem change? if at the time of the trial the cloakroom worker will be dismissed from the theater, and the criminals discovered?

Additional information:

After payment you will be available a link to the solution of this problem in the file of MS Word. It should be noted that the problem solutions put up for sale were successfully handed over in the period 2004-2019 and could be outdated. However, the general algorithm will always remain true.