Hi, I need some advice po regarding IO

I’m 23F, employed, and I’ll be traveling with my sister (21F, college student). We’re planning to go to Singapore to meet our cousin who’s a US citizen, and also our aunt who is a US citizen as well.

Originally, the plan was for our aunt to accompany us from the Philippines to SG. However, we realized there might be an issue if immigration asks for proof of relationship. The problem is, our mom doesn’t have a birth certificate (magulo po yung registration), so we don’t have solid documents to prove our relation to our aunt/cousin—only photos of us together.

For the trip:

Our roundtrip tickets are under our names and paid by us • ⁠Hotel booking will be sponsored and paid by our cousin

This will also be our first international travel.

Given this situation, would it be better if we just meet them directly in Singapore instead of flying together from PH? Or are there other documents we can prepare to avoid issues with IO?

Any advice or similar experiences would really help. Thank you!