Now that Marriott has absorbed Starwood, the old Starwood properties can be booked via the Marriott web site. This means that you can book via TopCashBack and get between 5.25% and 7.35% cash back on properties where this was not possible before. if you are a UK resident and not a TopCashBack member you can join via this link and we both benefit.
Of course if you have pre-paid your Starwood bookings this is not an option.
Othewise I would rebook your current stays in order to get the cashback as it’s pretty decent even at the lower level.
Starwood bookings already made are populating in merged Marriott accounts as of this morning.