Not sure how to handle ferret dying

Question
Hi! My name is Nadia, about a month ago I rescued two Ferrets one named Luna who is 4 years old and another named Bella who is 5. They came together and I was told to not separate them by the previous owner, the only issue is that Luna has a severe amount of Tumors and is an adrenal ferret. I took her to the vet and the vet said that she is too old for surgery and realistically its to the point where we cant really help her. I know I need to put her down but I am really worried about Bella, they have been together for awhile and I am not too sure how to go about this. I was thinking of maybe before putting down Luna I get a third ferret and introduce them to the pair I already have. The thing is I hear that you should let your ferrets pick their new friend but I am planning on rescuing another ferret which means less options and not many opportunities to bring my girls to check out the ferrets. What do you think I should do? Should I just not get another ferret and let Bella cope once Luna is gone, or should I get another ferret? I am also worried about her age she is 5 years old and the chances are I am going to get a younger ferret.. would that be okay? I know in their previous owner they were surrounded by tons of animals. The previous owner was bit of an animal collector had 20+ animals in her house including dogs, ferrets, birds.. so I was thinking maybe they would be used to different creatures. PLEASE HELP I am so confused and not clear on what is the right thing to do! I am also very sad because I have no had them long and wished If I got them earlier maybe the tumors would of been more under control for me to save her...

Answer
I am so sorry for you.  Probably, everyone you ask will answer this question differently.  In my own opinion, ferrets usually recover quite well from change.  If you decide to add another ferret, try for one a little closer in age to your existing ferrets so that their play levels are similar and the younger ferret doesn't become too much for the older ones.  If you adopt a new ferret, try to find one that has experience with other ferrets and that should help.  
Regarding the Luna, surgery is not the only options - their are medications you can use (lupron or deslorelin) which are excellent alternatives to surgery.  Sounds like your vet is not up to date on the recent adrenal options.