Like how does...

[innocentmonster]

Greg,how do you get a sim married to more than one sim?

[Miros1]

You have to do it with SimPE. Greg and I have both written tutorials on the subject.

For polygamous marriages, you don't want to change the neighborhood table. Instead you change the relationships of each Sim involved in the marriage so that they're all married to each other.

I'm going to be doing this soon, because I've got twin brothers in Uni who are pretty interested in each other's girlfriends. I intend to move them all in together, marry them off in couples, then fix up the other relationships in SimPE. Will post screenshots!

[Greg]

You can also do it with the Insimenator. Just set the mutual marriage flags.

But do look up those tutorials first. If you edit the neighbor relations table in SimPE instead of just setting the individual character's flags, your game will crash when you try to save a lot.

[Miros1]

My group marriage (2 brothers, who had two lightning bolts for each other's girlfriends) is working fairly nicely. However, it's been put on the back burner by the No Fugly Downtownies testing.

[innocentmonster]

Ok I now know how,I tried SimPE and it worked but do I have to make them all married to eachother,for example-Mortimer is married to Nina and Dina but none of them know that
Should I maked them know they are married to him?

[Miros1]

Yes. I left the brothers as brothers, but I set both brothers married to both girls and the girls married to each other as well.

[Greg]

(It's easier with the Insimenator. Really!)

[Miros1]

I like to understand how things work, so I do it by hand...