Originally Posted by
yosithezet
Most likely the would simply convert the Starwood account into a new Marriott account similarly to what happens when airlines merge. Create a new membership number, move the points into that new account, copy over all the details of the member. They wouldn’t want to have to maintain the Starwood systems in production mode any longer than necessary.
And they probably will not need to assign a new number. Most existing numbers, both SPG and MR, are supposed to work in the new system.