So Cybran's hives are a very strong unit, UEF have engineering stations which is a good alternatives for UEF. However Aeon and Seraphim do not a good early hive alternatives . Seraphim and Aeon SACU with the Rapid Fabricator is a good late game replacement however quite costly and slow. So they really have to depend on engineers resulting in having lots of engineers surrounding building causing bad path finding.
Now I do not like the idea of Seraphim and Aeon just getting their own hive building as I like the diversity in the factions. Also I am not sure on what is possible so here are some ideas.
Be able to combined engineers together.
So if you had 10 engineers of the same tech level you tell them to all combine together, now you have 1 engineer with the power of x10 engineers (maybe even give them a bonus boost as well), limit the max amount engineers that can be combined together. (Kind of like creating super engineers) could work the same way as a transport ship.
idea 2 when engineers are assisting they then allow units to passthrough themselves (not enemy units though) this removes the pathfinding issues and allows units to stack while assisting.
Idea 3 make hives and engineering stations T3, however this is not going to be a very popular change and I do not think is solves the issue.
So I am not sure on what is the best solution but I think both Seraphim and Aeon need something a little extra vs the hive/engineering station.
What are your Ideas and thoughts.