Does anyone know of what sites in Manila might be part of this bid?
I too have failed to find anything specific on Manila - but i would have thought that the Philippines would have used any such nomination as a chance to place the whole of/much of Intramuros on the List. It would seem that the name of the site would "require" that Manila was included? But the other end at Acapulco provides a similar problem - it is a bit "thin" on good quality historical remains as well - just yet another "Spanish fort" of which the List already has rather too many!
There is already a memorial to the Galleon trade at the Plaza Mexico inside Intramuros - have you seen it? https://en.wikipedia.org/wiki/Manila_galleon#/media/File:Manilajf9742_16.JPG
But it would seem that the Philippines would go for other locations too - e.g Ruined shipyards in Sorsogon for instance. The author of this article is employed at the National Museum in Manila and provides her e-mail address so you could e-mail her for more info on the possible shape of a nomination?http://www.themua.org/collections/files/original/34a74c76efdb951655b9bde1213812dc.pdf
And the nearby location of the first mass in the Philippines? How much "tangible" remains might be a problem however. http://rhescobal.tripod.com/losgaleonesbagatao/
This conference on the Trade held in 2015 ( http://nhcp.gov.ph/1729-2/
)mentions the Shipyards again and also the port of Palapag - a fair trip from Manila however! But Manila itself doesn't deem to figure - I guess its inclusion if at all would be symbolic and a way of getting another inscirbed site for the Capital.https://en.wikipedia.org/wiki/Palapag,_Northern_Samar
Note also the "Underwater Archaeology" aspects of a possible Nomination which could even take in sites in Pacific Island sites countries such as the Marianas and Guam?