Help exporting dual material AMF file in Slic3r 1.2.9

I am trying to figure out how to import two .stl files, merge them, and export them as an .amf file. This version of Slic3r looks different from the tutorials on their own website. I can’t figure out how to align the two objects on the plate before exporting. They lay out sequentially and for me to eyeball a drag and drop just doesn’t seem reasonable.

This is on version 1.2.9

Thanks for any help!