issue with father's middle name in birth certificate

please bear with me. our whole life, my sister and i have been instructed to use ESPIRITU as our father's middle name(sample name only for confidentiality purposes). I'm now 24 years old,my sis 21, and that's what we used for all our docs (school records, employment, government IDs, etc). It was not until last year when I was applying for a passport (already at the DFA so no time to change) when i noticed in my birth certificate na ESPRITU nakalagay (sample also. basically 1 letter is missing). i was nervous but my passport got approved. i brought it up with my parents then but they just brushed it aside. Even in my sister's birth cert ESPRITU is indicated.

Now, I'm planning to get married by November and while preparing for the needed docs, i recalled this issue. i confronted my parents and accdg to my father, he now uses ESPIRITU since that's what's in his birth cert. what happened pala was ESPIRITU talaga yung family nila but some time when he was still a kid, her mom changed their middle name to ESPRITU as she thinks it's "better". Since my grandma is long gone, they don't actually know how their name change was processed. growing up he used ESPRITU (it's in their marriage contract) but some time after my sister and i were born they saw na ESPIRITU yung nasa birth certificate nya so moving forward that's what he used (we just found out that his siblings, all girls, continue to use ESPRITU to this day). he didn't bother fixing the issue. when we asked him to help with this issue, he angrily insisted that this is our problem and that he has nothing to do with it.

How should we approach this issue? If left as is, would this be a problem for me & my sis? Our primary concern is the problems it may cause us in the long run, and if this will serve as an impediment for my upcoming wedding and any other id/loan applications. not so much on possible inheritance. so far we've had no trouble with requesting for documents. maybe it's not really checked or maybe the processors just don't notice.

Many thanks for taking the time to read my story! (Note: edited multiple times to improve flow )

After talking again with my family, it seems that the direction that my mother is leaning into is to just update our birth cert to ESPIRITU. i called the civil registrar's office and i was advised that if it's just one missing letter, it can be covered by RA 9048 thus eliminating the need for court petition.

Would like to seek your legal advice if it's the best course of action and if this is indeed covered by RA 9048. Another concern is with regards to the timeline. Accdg to the person I spoke to, if we went there today, they would give us a checklist and schedule us for interview/process on October pa. And then once approved, it would take another 2-3 months before it's finalized (finishing at around January/February next year). Is it also alright to proceed with the wedding in November using my current NSO birth certificate (birth cert required for marriage license) and to proceed with the purchase of a condo that we're currently finalizing (birth cert is also being required). If yes/no, how should we approach this?

Many thanks!

P.S. What should I use when requesting for CENOMAR and a birth certificate?

i agree that ra9048 is your best course of action. i wouldn't lose any sleep on a misspelled father's middle name.

Many thanks Atty!

So it's ok to proceed with the wedding and purchase of property using my current birth certificate? For the application forms wherein I'll be asked to input my father's middle name, should I use ESPRITU (as per my birth cert) or ESPIRITU (what's in all my docs / what my father would sign / what would be after corrections).

Also, since you mentioned that you wouldn't "lose any sleep" about this, do you think it's alright if we simply leave our birth certificate as it currently is and just continue use ESPIRITU?

Thank you very much!