Here is a comparison photo of the flowers of Hoya narcissiflora and an umbel of Hoya sp. Surigao Del Sur blooms:
Hoya narcissiflora Meets Hoya sp. Surigao Del Sur
Vermont Hoyas
A site about growing Hoyas in the Northeastern United States
Here is a comparison photo of the flowers of Hoya narcissiflora and an umbel of Hoya sp. Surigao Del Sur blooms: