If you do get another puppy (and even if you don't) please get Trixie spayed, and if you get a male puppy make sure you have him neutered.
make sure your fiance isn't allergic to whatever puppy you get.
(Someone recently got a Morkie and now is trying to rehome it because her son is allergic to it) so make 100% sure your fiance isn't going to be allergic to a new pet.
When I got my very first Yorkie I got a second one only weeks later, they got on fine. I have also had dogs further apart that got along fine.
It all depends on the dogs temperament.
Oh and:
