No, there's no way to do this in simultaneous. The best you can do is move them to the same sector on one turn, then combine them and order the attack the next.
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Cap'n Q
My first SE IV mod!
Hypermaze quadrant
The most merciful thing in the world, I think, is the inability of the
human mind to correlate all of its contents. We live on a placid
island of ignorance in the midst of black seas of infinity, and it was
not meant that we should go far. -- HP Lovecraft, "The Call of Cthulhu"