How can I add my name to child's birth certificate?

A lot of your question depends on how long the child has lived in Florida. If its been less than 6 months chances are that Maine still has jurisdiction. If Maine law is anything like Minnesota law it would be a matter of asking the court to amend the paternity order to direct that your name is added to the birth certificate. From there you'd have to transfer the Maine court order to Washington state for a Washington court to direct its vital statistics agency to amend the birth certificate. However you should consult an experienced attorney about why you think you need your name on the child's birth certificate as your goals may be more easily achieved by a manner other than amending the birth certificate.

This should have been done in Maine if that is where paternity was established. Since you attach no dates and don't say anything about what court ordered child support and a residential plan, it's impossible to advise where you need to go to court.

If the paternity acknowledgement did not change the name (look at the form- if it did then send off for a new birth certificate), then you should file suit in the county where the child has resided for the past six months.