HI there
Has Sassy been like this only since the pup arrived, in the last 4 weeks?
If so, she has been unsettled by the pup's arrival. If she destroys stuff when you have only been out/upstairs a short while, and hasn't before the pup's arrival, then she is showing signs of being stressed.....
Hopefully you may find it will all settle down of its own accord - if you are lucky!!!

Make sure Sassy gets lots of fuss and isn't told off when the pup is there for any misdemeanours, as she will associate this with the pup's arrival too. The pup won't miss fuss as he/she isn't used to it individuallyl anyway, whereas Sassy is.
Think too about whether, although Sassy does get on with the pup, she may feel a bit fed up if the pup is always trying to play when you are out/upstairs. It may be her way of saying "help" lemme outta here!!!"
Just a few ideas, anyway

Lindsay