Another COMMON misconception and I heard it recently from another Filipino, that recs. were burned. It may, for some, but that doesn't mean the recs. of your own ancestors were burned.
Even when I went to the Philippines finally, I made an effort to extract some church recs. to trace my paternal grandfather's side & my cousins said the same thing including one who is a nun and was with me. They waited for me and I came back about 1 1/2 hours later and they were surprised I traced a couple more generations and got the baptism of my cousin's father of whom they said they did not have, so that was the story back in the 1950s I believe. But here it was in 2004 and I managed to get the record.
What you need to do is to remove the historical past from your own lineage. And concentrate and what you have and work your way backwards as I suggested. Don't make assumptions based on history.
ANY embassy may or may not have recs of entry into the given area. However I don't know what the privacy policies are for the Phillipines or the Spanish embassy in the Philippines. Given that it is a long time ago, that I assume would not be a problem.
But you are talking about some made up story of conquistadores fighting lapu lapu, but that wasn't the case. It was Magellan and his crew that were killed on Mactan. And a couple of decades later the next ship captained by Ruy López de Villalobos that left Mexico with just under a crew of 400 on 6 galleon ships arriving in 1543. This is the same person that named the islands after Philip II, son of Charles V, Holy Roman Emperor.
I can understand the guesses or estimation based on previous facts. For example, I had a burial record of my grandmother's great-grandfather Esteban. I had found his burial rec. for 1875 and I estimated his age based on OTHER FACTS, that he was probably born around 1795. I found his siblings as well, their burial recs. and estimated it accordingly to which it made sense. The range I came up based on all the siblings ranged from 1776 - 1816.
Then I came across a burial record for his sister who died in 1866, but this time they listed her age, which was 95 years old. From that I was able to calculate an specific year - 1770. And that is more or less within the range of her other siblings including Esteban which I estimated at 1795. All of which fits perfectly in the range I estimated, but we are talking about 4 - 5 years of genealogy experience by this time.
So, if you do make any notation of a Chinese ancestor of whom you knew actually existed and to which line he belonged to (which of your grandparent descends from him) and the same for your Spanish relatives, then fine.
Rodriguez is such a common name but be sure to make sure that that specific surname was not handpicked from El Catalogo Alfabetico de Apellidos of 1849. Most importantly if you start researching the church records, you'll know for sure if that name came from that book or if it was handed down non-stop generation after generation from a foreign ancestor.
But you mentioned you're not sure if your great-grandfather did a family tree? Do you mean that it exists for your family that someone already gathered some info. on the family?