I can tell you that I just added a 2nd yorkie to our home and it was a Godsend!! Maggie has a playmate her size and she has loved every minute of it. I honestly can't believe I waited so long to get another! maggie was a year and a half old when i got tessa...but i think adding a 2nd when the 1st one is still young is a GREAT idea.
GO FOR IT
oh..and be sure to post pics when you do