Peter, You have gone further back than I was able to do...so i don't even know if those are relatives.
I have Pedro de Aguirre m. Maria de Sagardia 31 Mar. 1671 in Aranaz, Navarra, Spain. Unfortunately the record did not give mention as to Pedro's parents or where he came from.
Most of the information I have I got from the "Echoes of the Conquistadores" written by Yginio Aguirre. Luckily that picked up where I had gotten to on my own. I did get the microfiche just to verify some of the information.
I was wondering if you were using other resources than the FHC???