To a Filipina lady, her family will always remain at the top of her priority list, and not just her family, but a large extended family. Respect for her family's elders had been instilled in her young mind since her cradle days, so your acceptance and the approval of her family as your husband-to-be is a vital issue.
In the olden days, when a man wants to marry his girlfriend, he had to take his parents and relatives with him (not to mention tons of food) and propose in front of the girl's family and her whole clan. The girl does not have much say in the arrangements.
If the elders reach a compromise and approve of the marriage, the husband-to-be will stay behind and serve his girlfriend's family for a few months, chopping wood and fetching water from the spring, taking care of the family's animals and helping her father in the farm. Even then, there are instances when the family finds something they disapprove of and the marriage will not push through.
You need not be alarmed because these are times gone by. You will not be required or expected to do service but her family would of course like to meet you.
However, if your girlfriend did not tell her parents or family about you, be prepared for the worst. Her father or brothers may wave a shining sword under your nose, chase you out of the house or loosen the dogs (and this is not impossible) by your sudden appearance! In truth, they feel threatened that you are going to whisk off a member of their family away.
This is also true if their daughter is very young and they pinned such high hopes for her, or when they found out you are older than her father by a couple of decades and you will take her away to your country and they will not be there to protect her.
Old-fashioned parents have this pre-conceived notion that foreigners are never serious with their relationships and marriages, and they have no desire to have their daughter join the list of your abandoned victims. Honestly, they fear for their daughter and do not relish the thought of their child leaving them to go off in a far-away land with a stranger.
It is just fair for you to assure them that their daughter will be in good hands with you. It is important that you show then that you are sincere and that your intention towards their daughter is true (if you really are) and that you are not a competition against their daughter but an ally for her bright future.
Make friends with them and join family activities to fit in. Capture the weakness of her parents and family members, and appreciate the close family ties they shared.
Treat your girlfriend like a princess and serve her in front of her parents and family. If you remember your girlfriend's family's birthdays, anniversaries, or other occasions, then that would even be better.