Paternity

My daughter is 7 years old. The acknowledgement of paternity was signed at her birth. However, during the first 2 years of her life her "father" denied that she was his. For the next 5 years he has been paying elective child support. I had been with 2 people at the time of conception and for many years have wondered if he is truly her father as they do not look alike and the clear possibility of her not being his. Can I still get an Order of Filiation even after this time? What do I have to do in order to get one? Will he have to submit to testing or can he decline?