There is, in fact, fairly general agreement on what to do about requests for extra guests, assuming one really can't accommodate them.

The family had even rented folding chairs to accommodate extra guests.

Oh dear - just when we've got three extra guests in the house too.

Some can also serve as auxiliary tables (often called the children's table) for extra guests.

Chaos ensues as they are called to a local party - with one extra hairy guest!

After you seated us at a table for four, I realized that I'd invited two extra guests.

She refrained from adding: because there was a reasonable chance Jason would turn up as an extra guest.

Millie had already pulled up another table to accommodate the extra guests, and brought out a new pitcher of beer.

It was always there, standing in the corner of the room like a silent extra guest.

The hosts showed their flexibility when almost 1,000 extra guests arrived, most of them aides and officials rather than athletes.