Hmmm...I checked out the guide to Lisbon
but unfortunately it doesn't to touch on your issues with citizenship. I found thedeclaration requesting your citizenship
, but it is in Portuguese so I am not sure if that is helpful
The other requirements appear to be:
Birth certificate (long form), translated to portuguese and certified by the portuguese diplomatic or consular authority;
Your Portuguese family member's birth certificate (long form).;
Your passport or ID
For the best advice, you need to consult with the closest Portuguese consulate. Best of luck!