Direct and OTA Bookings Back-to-Back
 

I have a stay coming up at the Prince Gallery Tokyo. I've already booked a 4 night stay, but may end up adding another night at the tail end. The 4 nights were booked directly with Marriott, but I'm thinking of booking the last night through AMEX Travel (Not FHR, just the regular Amex Travel). I have 2 questions:
1. Would they merge my 2 reservations at check-in if I mention it?
2. Would they give me PP benefits for the entire stay? Or only the 4 nights I booked direct with Marriott?

Anyone have experience with something like this?

1. I suggest you write them before check-in. I never had problems with merging reservations.
2. Really depends on the hotel/country/cultural norms. However, Japanese culture is very respectful of the rules, so I would not count much on getting benefits on the last night. Everything is done by the book in this country.