You cannot be sure how Tinky or even Jupiter acts if a baby kitten comes in. They both are stressed at the moment because they felt what was going on. If you look at PayitForward or Sasvermont, it is not always sure that cats easily accept a newcomer.
At the moment I would at least wait until Tinky and Jupiter feel both well in their situation. Anyway 6 weeks is very early for a baby to leave his mother. 8-10 weeks would be better.