Basically it boils down to this: were there terms?
If there were, you have to abide by them. If there were not, they have no say in what you do.
If their terms say nothing about modifying the cover, again, they have no say.
If there were, you have to abide by them. If there were not, they have no say in what you do.
If their terms say nothing about modifying the cover, again, they have no say.