Drops from bosses in 7.3.5

Hello. There are a number of questions about the drop in Legion.

  1. Is it possible to change the drop rate of items when players use the Seal of Broken Fate after killing bosses? I would like to make sure that some thing from this boss falls with a 100% probability.

  2. How to increase the amount of loot from bosses? If there are less than 10 players, then one thing falls. If more than 10, then two, and so on. Is there any way you can increase the number of things? Or make it so that one thing falls 100% for each player?
    Sorry if I posted a question in the wrong topic.