Places near Sheung shui like Ruby Tuesday in Shatin New town plaza or more ideally suitable would be excellent. Location anywhere in HongKong would be fine too.
It will be a small party of me, wife, grandmother and some cousins.
anywhere is ok as the party is for the family and NOT for the baby in question.
if you tell ruby tuesday(in shatin) that it's the baby's birthday, they'll bring a "tall cake" out and the staff will sing happy birthday. (at least they did for my son in february!)