The border east of Roxas Boulevard is well attested. See for example this
map of Barangay 1 in Pasay,[1] and this map of Manila.[2]
What's not exactly clear though is the border west of Roxas Boulevard. I
once read an article about a court case wherein Pasay and Manila were
disputing to which
The northernmost boundary of Pasay doesn't look right to me
https://www.openstreetmap.org/relation/113858#map=15/14.5533/120.9955
Most of the rest of it is following roads, rivers, coast etc, but it looks like
this doesn't follow anything in particular.
Jim
