These can be awkward as hell.  Or not. Just depends on how you handle them.  First off, major congrats on maintaining a sugar arrangement for 9 years!  That might be some kind of record.  We all know that arrangements all come to an end eventually,  but eventually is usually much sooner than 9 years!  I had a date yesterday with an amazingly beautiful, sexual SB who will be leaving my state to pursue career opportunities very soon. I'll get to see her one more time at the most.  But our arrangement lasted 9 months, not years!

But back to your original question.  When you see your new baby again I would just be totally open and honest with her.  Does she already know you are married?  If not, now's the time to tell her.  If she is at all savvy about sugar dating she should not be surprised.  Presumably your last SB knew about your home situation, right?  Tell the new baby that you have to keep your relationship with her a secret from your wife.  Many young SBs love being the secret "other woman" and will relish that role.  

You might be worrying about her eventually revealing her SB status to your wife, either intentionally or unintentionally.  But she has a lot to lose in that case.  She could lose her job if someone on her route reported she was messing in  their domestic affairs.  She has a big incentive to keep her visits to your home totally professional at all times.  

Finally, if you've been lurking here for 10 years you may recall that I often beat the drum to popularize (and proselytize!) polyamory as the ideal lifestyle, especially for sugar daters.  I know that most people in a long term marriage defined as monogamous think it's impossible to change.  But your wife might be more open minded than you think.  You could start by bringing a few books into the house.  Maybe start with "The ethical slut" or "Polysecure". Open the conversation about how lots of people have discovered they can maintain a committed long term marriage at home, and still get more of their needs met by enjoying intimate relationships with others.  It's possible!  My wife and I have done it, and our loving relationship at home is stringer than everything.  Best of luck my friend, and let us know how it plays out!

Remember that she has a lot to lose too.
If she wants a good SD she will probably be delivering his packages too. Agree that you should have a conversation, hope it works out.

The best arrangements are founded on transparency and trust on key issues.  But there must be limits,  

 
Part of that trust revolves around who else you or she may be fucking. Not that you need names/dates or relationship details. But you need to trust that if she is going to sleep with other people, she will do it safely (however you define safe). And she needs to trust the same of you.  I'm no expert on arrangements where one or both are married and don't have explicit "permission" to see others. And I'll defer to Papa Sweet for his expertise on polyamory - my experience in that area was much less successful than his.

 
But other than the now required discussion you must have about your marital status (which must happen ASAP before she makes ill-informed decisions on her own) here's some issues/risks you may need to consider:  

 
1. It looks like she will be an almost daily visitor to your home. Fortunately, those will occur at fairly predictable times. So you might want to be hyper-aware of what will be happening at your house during mail delivery windows.  
2. As part of your discussion, you must agree that both of you will stay "professional" when she is there. I suggest that means:  
A.  No acknowledgement that you know each other outside the obvious.
B. No idle chit chat when she's on your property. Say "hi" or "thanks" and close the door.
C. She should avoid chatting with your wife (or kids?) and neighbors. Just deliver and leave.
D. You should never refer to her by her name - especially when she is not there!  
E. If you two have some disagreement (or fight) - keep it out of her "workplace."
3. Now here are the big questions:  
A. Can you trust her not to blow your deal to your wife, kids and neighbors, no matter how good or bad your relationship is?  
B. Same question, but no matter how good or bad your relationship with your wife is?
4. Is she your only SB? If not, be aware that you probably can no longer use some cover lie about being on travel as an excuse to not see her for a while.  Nor can you use the "my buddy is in town for a few days" cover lie.  

 
Other than these, I assume you are already skilled and aware of how to keep your sugaring hidden from your wife.  

 
Finally, spend some serious time thinking about all the negative "what if" scenarios.  What if:  
1. She want to end and you don't?
2. You want to end she doesn't?
3. She lacks the maturity/discipline to follow the special rules when she is working?
4. You slip up and do or say something stupid in front of your wife/kids/neighbors? Do you have plausible cover stories ready? Have you pre-fabricated evidence to support those stories?  

 
Ultimately, make a smart decision (i.e.: without using your dick) about whether all the risks are worth the prize.  After a 9-year arrangement you pulled a hottie rather quickly. So you can likely do so again anytime.  

 
I'll close with story of my own. My current #1 SB - 20-year old Viet Spinner, lives with her mother and brother. They have moved 3 times in the last year, finally settling in an apartment. She does not own a car and I have been either picking her up or sending an Uber to get her. (I'm single, so I host at my house.)  But her new place is just 1.25 miles from mine! She does not know I see other SB's (she never asked) and we see each other 2-3 times a month.  

 
When she told me her new address I nearly panicked. She is now walking distance (maybe 15 minutes) from my house. She could potentially show up on my porch anytime she wanted to.  And since I have 3 Asians in my A-List rotation (well, talking about THAT is for another post!), I could literally be balls deep when my Ring Doorbell chime goes off!  

 
Fortunately, that hasn't happened - yet.  Although she is only 20 (we started while she was 19) she's fairly savvy about the sugar environment. So all is well for now.  

 
Lesson learned: Definitely CONSIDER all the risks. Then relax and give the situation time to prove those risks are not likely to manifest.  

 
Life is good

 
The Cat

Even though I'm married, I'll let any SB know who I am if we've gone or are about to go BCD.  I'm a little less ready to do so at the initial negotiation stage.   But once you are fucking, your ability to protect yourself from exposure is mostly illusionary.  It's mutual trust.  

And for that reason, it's important to me that any new SB knows I see other women.  So usually either by text or at our first coffee date (but def before our first BCD) I let them know that there are others in my life, just as I assume there will be others in hers.  And I prefer it that way.  I'd be uncomfortable if I thought she was relying on me to get 100% of her needs met.  Sometimes this leads to conversations about our other lovers, sometimes not.  But I'm not seeking anything exclusive and I don't want them to assume otherwise.  If there was any chance one of my SBs could show up at my house unannounced I'd be certain to ask them not to ever do that.  I might be busy with someone else!  Just as I would never show up at her place unannounced for the very same reason.  Surprise visits are not a good thing in sugar dating.