I don't know if you are coming back to YT so you may never read this, but I am still going to post it, in hopes that you will read this...
YT is a wonderful place, there are so many knowledgable, caring and responsible Yorkie Moms and Dads. We love these guys so much and we only want what best for them.
I am not in your shoes so I don't know your true situation and how you feel. I am in my shoes and know the things that I would do and the things I would not do. I won't preach to you but I would like to offer suggestions that other very knowledgable and experienced people have said over and over.
It would be really great if the 2 boys - brothers - could spend the rest of their lives together, so if you can please try to keep them together, it will be less stressful for them.
Try to attached a small 'adoption fee'. Reason being is that there so many horrible people out there in this world. I don't want to go into details b/c it might upset you more in your current condition, but for the best interest of your boys, consider asking for a small adoption fee to deter any 'bad elements' from crawling out of the wood works. I have seen people turn around and than donate that small adoption fees to a rescue, this way you could be helping others in need too.
Which brings me to the last suggestions: Yorkie Rescue - I will list a few for you, but that would probably be your best bet, to surrender them to a reputable Yorkie Rescue. They are experienced and have the people to be able to get your boys into the best suited forever home.
Below are sites dedicating to rescuing and re-homing Yorkshire Terriers.
Canadian Yorkshire Terrier Rescue
http://www.canadianyorkshireterrierrescue.com
Rescue Me Yorkie Rescue
http://www.yorkierescueme.com
Save a Yorkie Rescue
http://www.saveayorkierescue.org
United Yorkie Rescue
http://www.unitedyorkierescue.org
Yorkie Haven Rescue
http://www.yorkiehavenrescue.com
Yorkies Inc.
http://www.yorkiesinc.com/AvailableYorkies.htm
Yorkie Rescue Colorado
http://yorkierescuecolorado.com/home.html
Yorkshire Terrier Club of Los Angeles Rescue
http://members.cox.net/ytclarescue
Yorkshire Terrier National Network
http://www.yorkshireterrierrescue.com
I wish your boys nothing but the best - I hope that they find their forever home, together.