I can speak from my corner, am married to a Filipinos lady in Canada. In the process to adopt my step daughter, the first question the lawyer asked was the situation with the biological father. Then she said adoption is granted with preference to married couple because the welfare of the child is the paramount concern.
Being an international adoption, not so much for the Philippines government, but for Western countries there are tight laws out of fears of human trafficking.
A word of caution, it is a lengthy and costly process, western embassies in Manila are aware of the situation in the Philippines so my suggestion is play by the rules.
Try these links:
http://www.dswd.gov.ph/faq.php
http://www.dswd.gov.ph/faqdetails.php?id=49
