If you mean, would a new plant produced by layering or as a cutting from a parent plant of one sex, change to the other sex, then I think the answer is no, the layering/cutting is a clone and would grow true to the parent.
I am not a botanist and I don't know if all those plants you mentioned ARE dioecious though I know the coccoloba is.
I was told once that some seedlings from male/female only plants, MAY "change sex" as they become adult plants but that's not the issue for you.
I'm not a biologist either, though I've read that people can chemically alter some plants to produce flowers of another sex but that is a one-way street, only female to male never the other way round. You could google, but it sounds like the sort of chemicals used, you might not really want in the makeup of a plant that you hoped would produce edible fruit .
I would imagine you have only two choices - if you know you have female plants of the species you mentioned, you have to find someone growing the other, or a source of pollen elsewhere for fertilization. Or, if you can get fresh seed, you may be able to grow up plants of both sex so that you have the possibility of in-house fertilization for fruit in future.
It sounds a bit like a project you might share with other fruit-eating bird fanciers who probably have the same problem sourcing organic native fruit.

I'm no expert, but Ms Google tells me that the Plum Pine and Sea Grape have separate male and female trees. Since you are getting fruit, your trees are both female but there are male trees within pollination range.

Layering does not work with all trees, but if it does the flowers will continue to be pollinated from the nearby tree.

However, since you have no control over these 'foreign' trees, I would suggest that you grown some of your seeds. Once they flower, you can identify the male plants and cull out all but one. Or buy a male tree from a specialist nursery.

Elderberries carry better crops if they are cross pollinated with another variety. They will grow from cuttings.

As far as I can work out, the Blue Quandong carries both male and female flowers on the one tree.

Daleys Fruit Tree Nursery has a forum with lots of committed growers of tropical and semi-tropical fruit trees who could help you.

Here is a link that might be useful: Daleys Fruit Tree Nursery