This is a tricky one! Forgive the novel.
I can understand both yours and your wife's opinions and viewpoints.
As everyone else has said, after all the discussion and guidelines in place, you'll most likely find that you learn the most actually doing it.
My girlfriend and I say that ex-lovers from the first 6 months of our relationship were "Casualties of The Great Poly War"
Because we thought we were totally ready, knew everything and had it all figured out. We did great for people who knew nothing, but we still knew nothing until that huge poly ball started rolling.
We made rubbish people choices. We expected too much from each other's people choices.
We picked some toxic people. People who manipulated and played games and tried to make each of us jealous of their relationships with us.
We also expected to absolutely love each other's play partners, all the time.
My girlfriend ended up essentially using her veto card on three of my girlfriends. Three in a row. I was in love with one. We realised that this wasn't good. Things had to change.
In an ideal world, everyone's friendly, ethical and considerate of each other. In reality, we have to consider how much things will actually effect us and our relationship.
Why do we judge?
Sometimes... and I do not mean this rudely... we can get on our ethical high horse (I'm renown for it) for two reasons:
1. We're in judgmental mode, because we're not on the fun end of that delicious thing called temptation. And being able to give into it. "I want, I want, I want... oh? I can have? Gimme!!" When you're there, rushing with hormones, you're willing to overlook certain things.
2. We are deep... deep... down... trying to come up with reasons for this not to go ahead just yet.
I'm not saying that I'm right... I'm saying that it might be worth considering?
If this helps at all....
A little story..
We actively try to pick partners that our primary partners are happy with. It sounds like you and your wife have a similar idea.
I have a problem with one of my girlfriend's potential play partners.
He's flaky, messes her about, messes with her head by being all intense and delicious, then disappearing. I've seen her upset over him so many times. I truly cannot stand the guy.
My lady knows my feelings, but knows I would never, ever veto the spineless little sap...
What's really going on in my head though?
Yes, a big part is "I think he's a bit of an idiot, I don't like to see her hurt and I'd selfishly prefer it if I could like the guy".
What is that tiny bit in the back of my mind? That tiny, tiny truth? "She's intoxicated with him. I'm scared of that."
So, I could let that take over and keep telling her and myself that I just don't think he's a good ethical choice. But I can't let that fear take over.
More "I'm poly" experience babble in the hopes of helping you...
I expect my primary girlfriend to tell her secondary partners about me.
Ideally, if they're long-term potentials, I expect to meet them.
I expect them to at least be civil to me.
I expect them to respect our relationship and the guidelines we have.
My girlfriend expects the same in return.
That's our joint ethical code.
Ultimately, your ethics are your own. Your wife's ethics are hers. Ideally, you'll get to the same place, or compromise.
The ethics of secondary partners? That really depends on how much interaction they are going to have with each of you and both of you as a couple.
I definitely would not expect my secondaries to meet each other. God, that might be awkward for them. But they do know about each other.
I personally prefer people who are honest. I pick honest secondary partners. My girlfriend is a little less strict on that. I won't date anyone who's married, when their spouse doesn't know what's going on. My girlfriend will. If I don't like my girlfriend's ethics, I don't have to stay with her. But as long as she's safe, and keeps my sexual health safe, she is essentially free to be with whoever she wants. If that gets her into deep water, that's her pool to swim in. Silly wench.
What can you do?
- expect the first 6 months to be a period of mistakes and learning
- expect to make some silly decisions, because you're both likely to act like hormone crazed teenagers
- be kind to each other and keep communicating
In terms of sexual safety. Yes, there's always a risk if our partner's partner sleeps around like their bits are about to fall off.
You can negotiate this by insisting that you both use condoms with your secondary partners. You can suggest that she asks him for a certificate of clean sexual health. If bodily fluids are exchanged, you can get an STD test. You should get those regularly anyway, once you start being actively poly - even if you stick with the same partners.
Anyway... novel over... I hope that some of this helps.