Will alprazolam show a false positive for nordiazepam and or oxazepam. the confirmation test was done via gc/ms from the lab i use. ?

No: Gas chromatography and mass spectrometry are very specific assays for each of these compounds (they detect the metabolites of each compound distinctly). In any event, these are all drugs of the same class (benzodiazepines).

Probably yes: My educated "guess" is that most drug blood screening is geared toward "groups" or "classes" of substances. Alprazolam, diazepam, lorazepam, and the others you mentioned are all considered to be in the class of benzodiazopine derivatives. Use of any of them will trigger a positive response, but is not specific to which is in your system. Other classes include thc, cocaine, crystal meth, etoh, etc.