But surely you could have a private handfasting ceremony. You can keep it small and on the downlow, inviting a limited number of guests you can trust to be discreet.
I wouldn't count on that in the case of Australia. My advice would be to avoid ANY kind of ceremony. Detail:
guests you can trust to be discreet
Unfortunately, humans being what we are, very good friends
can turn into bitter enemies, and some might be so mean as to want "revenge" for some imagined slight... and be willing to denounce the wife for bigamy (or use their knowledge for some kind of blackmail).
ryancvg, you write that
"He has offered to marry thru religious ceremony". This could mean one (or both) of 2 things:
a) That he suggests a religious ceremony so that they don't have a civil (state-organised) wedding, in this way avoiding the legal charge of bigamy.
b) That he is a religious person and needs to feel that he is "properly married before God".
In either case, he needs to be convinced that he has to give up this idea. A religious ceremony is just as legal (or, in this case, illegal) as a civil one. And - as
Emm has pointed out - this one would be strictly dealt with under Australian law. 5 years prison! (And they're NOT going to allow the 3 of you to share a cell.)
Buy a bottle of champagne (or - if you're non-drinkers - mineral water) if you like, and the 3 of you drink to your future commitment.
BUT
Take the advice of many who have already written: "Don't rush into this!" (The living together in the same house.)
Honestly your wife and her bf need to slow things down. They are high on NRE.
It occurs to me that you might not know what NRE is. It stands for "new relationship energy" and concerns that feeling when somebody has just fallen in love / started a new relationship and everythying is looking rosy, "Nothing could possibly go wrong: we were made for each other and will love each other until the mountains crumble!" Great feeling... but not always a sound one for making important decisions or life-changing moves.
For me, polyamory does not mean 3 people having sex together. There must be emotional commitment. I'm glad to read that you like this guy, and - since you're both bi and having a threesome - I assume that there's also an emotional bond between you two men.
To answer your question: Yes, of course it can work. But - like all relationships - it will need commitment and energy, willingness to adapt, and especially respect for the feelings of EVERYBODY in the dynamic.
The fact that you posed this question makes me think that you have some doubts. (At least
you aren't being blinded by NRE!) The fact that your wife still loves you and doesn't want to lose you, the fact that you don't want to lose her, the fact that the new boyfriend doesn't want her to divorce you... they all point to the possibility of you accomodating each other in a 3-way relationship.
I think that the 3 of you need to sit down together and talk about all of this seriously and calmly. It doesn't have to be in one mammoth session. Don't make it heavy or uncomfortable. But do give it the consideration that it deserves.
Then break out the mineral water!