You can book a room for 1 guest and add a 2nd guest name. This allows the second guest to check in.
this is particularly useful for Diamonds as the 2nd guest is always free but if you select 2 adults the price can go up so we always select 1 adult,

When the member is not physically checked in, technically the Honors benefits are not given, I have booked rooms for my family before where I was not there and so far have not seen an instance where it happened, but if it does it is within the rules and I would not complain.

Globalist