import multiple files "EPS" in one window in illustrator

If you would like to import all of the file objects simultaneously, use InDesign for the import process and to gridify the entire set. Then, copy it from InDesign and paste it to Illustrator.

To import the file objects simultaneously, you may have to first gather all of them into the same folder. Then, using InDesign, create a temporary document, press Ctrl+D (Cmd+D on a Mac), select and "Open" all of the files, drag a rectangle for the total grid area, before releasing the mouse button, tap the right-arrow key to add columns and the up-arrow key to add rows. The opposing left- and down-arrow keys will remove the columns and rows, respectively. Once you release the mouse button, objects for all of the selected files will be sized to fit within each grid cell. Lastly, with the entire grid still selected, copy, switch to Ilustrator, and paste. Voila!

Another method that worked for me is to combine all file objects using Acrobat into a single document and open it using Illustrator. This is generally slower for some reason, but is useful when the original or relative image sizes are important. Using this method, Illustrator will prompt you with the option to import all pages or a specific range. Note that placing it will not give you the options for all pages or a page range.

Have these files been created in Illustrator?

If so, then they have 2 "forks" in one file: an EPS and an AI. The EPS fork just contains stuff that Illustrator 3 could handle (20 years ago). Everything else, your effects, live objects, brushes, whatever, is outlined to shapes.

The AI part is fully editable in version you specified when saving the file.

So now you Place those EPS files. When you do that, you access the EPS part of the files. So you basically ruin your work. Is that what you want to do?