Can an EOCR Be Used for Multiple Feeder Protection?

In principle, yes! you can use! Only you need a summation CT whose multiple primary windings will be from the CTs of each of the feeders you want to protect and the Summation CT's single secondary will be connected to your EOCR. The summation CT ratio should be appropriately specified.

But, such an arrangement is not advisable as discriminatory protection is not possible.