Laurie - Great job of successfully growing this nice group of cuttings. If they were mine, I would leave them together, repot as needed, and pruning to maintain it to any shape you prefer.
It is not easy to get Ficus cuttings to develop into tree forms with a single trunk. The single-trunk trees that you see for sale were usually started in nurseries with much larger rooting stocks. In greenhouses and in warm climates, they will develop nice thick trunks.
If you decide not to keep it in bush form, you might consider making a braided trunk. To do that, remove all but 3 or 4 stems that are close to one another in the pot. Strip off the lower leaves of those remaining stems and braid them together while they are still young and pliable. You may need some soft string or yearn to hold the braided stems in place until they grow together. You do not need to unpot them to do this. You may need to prune off some more lower leaves until the stems are well merged. In time, the stems will braid into a single trunk and they will develop a nice canopy of leaves. The more light you can provide, the better.
This is not easy but is a challenge I am sure you can manage as you seem to have a good touch with your plants.