(2018-01-14, 12:12)Milan Vančura Wrote: The easiest way is to simply open the other file, too. Then switch back to the first one (hotkey "End") and find the other one in the part bin, section "all models open" or similar name.
FYI: you can also use shift+ins after switching from the just opened file to the main model. shift+ins will add the last used session's model to the current one. So you could do "Open second ldr" -> END -> SHIFT+INS