You have to propose, and if they like each other enough, the other person will say yes, and they will produce a ring from nowhere. Although, you can't actually have a proper wedding seeing as you are on a deserted island.
You dont.
you can find them in all different places on different islands
You can have sims get married but they can not have children
Use another sim to make death daisy poison and come back to life.
no
craft it
You can go to them and get the death daisies and then make a death daisy potion to make them come back to life....
In crates on the beach
no
well how do you get tearcous seaweed on sims2 castaway ds
The mansion Barlow
Sorry i don't think so i tried too and they just can't sleep together somehow...