3 trunks ficus fusion update

6 weeks ago I started to fuse 3 ficus religiosa seedlings. Here is some progression. 

This is how they looked on the fusion day:

This is 3 weeks after fusion

This is now, 3 more weeks later:

Trunks at ground level have practically fused, wire is hardly visible. This is in less than two months!

One trunk is blackened in the bottom by some reason. It doesn't look rotten, just black.

Trees grow vigorously. During this time, they grew from 20cm to 50cm tall. I have to periodically add new wires on the top to keep them connected.

This is full view of the composition, after couple new wires added and some minor defoliation. New leaves grow red first, like the one on top. Later they become green and very large. Since trees were not clones, they look a bit different, have different height and width. I don't think it's a problem, future trimming should equalize them. Currently my plan is to let them grow unrestricted until they reach roof of greenhouse (it's ten more centimeters), then trim top to encourage branch growth. Branches should make trunks even thicker and I can bind them to the main stem as well.