Options > Attribute Manager
Click on the fills tab, then on the right size, click Open to open the other file. Select the fills that you want/need and - depending on your need - append or overwrite them into the active file.
Cheers,
Karl
One of the forum moderators
AC 28 USA and earlier • macOS Sonoma 14.7.1, MacBook Pro M2 Max 12CPU/30GPU cores, 32GB