I am 56 years old and I recently received negative paternity results from a spanish court appointed lab in Sevilla , Spain regarding half siblings, biological father is deceased. My mother will not accept the results that say I am excluded from being their fathers daughter. 7 markers out of 24 were not a match , all 4 half siblings and their mother were tested. Should my mother and I have our DNA tested here in the United States where we live? I cannot afford exhuming their fathers body. I was told that is the only 100% way of knowing whether this man is my biological father. I'm devastated from believing this for 37 years.
From what I understand of the paternity and sibling tests, because the mother of your potential half-siblings tested, the results should be certain (with a negligible uncertainty value). I would like to emphasize, though, that I'm not particularly knowledgable about this type of testing.
If you are interested in finding out who your biological father is, I recommend that you and your mother do direct-to-consumer DNA tests, starting with AncestryDNA and 23andme. From there, results can be uploaded to FamilyTreeDNA, MyHeritage, FindMyPast/LivingDNA, and GEDmatch. This will give you the largest pool of genetic relatives, and you will be able to sort out your maternal and paternal matches.
If you are on Facebook, I recommend joining the groups DNA Detectives and DD Social. Many of their members have been through what you're experiencing now, and will both be able to help you process your emotions and find what the best path forward for you will be.