Hi WendyT,
I see no reason why your friend can't further object to the amended application. An amended application includes information or excludes information that may negate an original objection. Therefore, submitting your objection again and explaining why the amendment still does not address your concerns and why your original concern remains is valuable information for the council. However, if the amendment is on something trivial such as a spelling mistake or matter unrelated to your original objection, and the provision raising your original objection remains, there wouldn't be much need to object again unless the original objection is only tried to one application reference and the amendment voided the old reference and created a new application.