I don't have a great understanding of the algorithms here, but I have a question.

If I had some data encrypted with these tools, which I made public for multiple entities to process, is it possible for me to allow them to add data to the encrypted system? i.e., is there a way for multiple entities to add more data to the encrypted data (and do calculations with the encrypted contents) while only one party is able to extract the results of the whole resulting collection of data?