The correct answer from the Andy Maly's old UF errata pages is:
17.8 If Groups A & C each transfer a man to Group B simultaneously, can B receive both of them with one action?
Andy was developing UF 2000 for MMP and had been the semi-official errata keeper for UF after AH was sold. He had them on his web site with his old service provider,
I have a Microsoft Word copy which I'll post here.