My wedding is only a couple of months away and things are going really well, but our numbers while fixed to 100 invites (expecting between 80 - 100 to attend) before shot up to 115 just before mailing them out because of last minute family interference.  Not sure how many of those extras will show.

Now, in the replies a lot of people who only got one invite because we thought they were single, have accepted with a plus one. It seems that all of a sudden people (especially friends) who weren't in a relationship are now in one and want to bring a date.

There are two issues: 1) Budgetwise an extra table or two will cause our costs to balloon.  2) There isnt physical space in the Church (its a small church), and adding a table in the venue will mean that people will in another room.

As much as I like peoples enthousiasm for attending and want to include, I need to have some limits. What is a tactful way to handle this?

We thought sending out an invite with one name one it was clear that there was no plus one, but several people seem to have missed that...