You don't really have to replant all these separately. In the case with forest planting, that can actually be a disadvantage of sorts, as when you recombine them years down the road, the branch structures on individual trees will inevitably conflict and you wind up chopping some off and having to regrow new ones to fill in. Believe me, this is a hassle, as you will wind up cutting off branches that you've spent perhaps years growing...
Also growing them together now will enable them to form a solid root mass, instead of individual masses that inevitably have to be cut down and reformed to make a cohesive forest down the road. With individual root masses, you will also have stability and support problems when you recombine--trees will want to flop over, etc.
A forest with meshed root mass is a lot easier to handle when root pruning.
Of course, all this means you have to be happy with how the trunks currently relate to one another now. Trunks that flow together visually are the anchor of good forest bonsai. Branching is secondary, really (healing trunk scars is about fifth on the list for now--it will happen pretty quickly wiht tridents anyhow-even with minimal branching at the scars)
If this were mine, I'd forget about healing the scars and select the apex shoot(s) on each tree, then select approrpiate branching shoots down the trunk, keeping in mind that those shoots should mesh into an overall design for the forest.
You want to select outward growing branches on each trunk (edit all branching that grows back into the interior of the planting)--with an eye to making an overall triagular (ish) pattern with those branches. You are basically treating the forest as a single tree in overall design, only with many trunks, instead of one...
Also, what are you growing these in? Looks like sand...