Squiff85 who do they want to leave out?
The average cost of a wedding may be 20k, but if it is people are, on average, insane :o A wedding is one day, one day, think of all the wonderful things you could do with 20k... A brand new family car, a deposit for a house, a whole year off work travelling the world, do a masters degree...
But that is beside the point I suppose, if you have 18k to give and are happy to have it spent on a one day party, just not with the guest list for the party (I did think guest list would be the big deal :o )
When we told my mother we were going to get married she went off and told all sorts of her friends and distant relations whom I hadn't seen since I was a baby etc. that they were invited - really, really, really stressed me and my DH out as we weren't that comfortable with the whole "wedding" thing, just wanted to be married, and would have been happy to go to a registry office quietly and not invite anyone at all... having a "wedding" at all was in a large part for the parents, and we wanted a small, informal, one with people we actually knew, not a party for my mother's friends at which we would be some kind of performing seals...
So I sympathise very much with people not wanting a long guest list of "friends of the family" who are actually their parents friends, and extended family members whom the parent/s want to show off their offspring getting married to, but who in all honesty mean less to the couple getting married than their postman or the lady at the corner shop (who are presumably not usually invited :o )
It used to be the parents party, but lots of things used to happen which are now not remotely normal - parents used to forbid their children from marrying if they chose and adult children used to go along with it (I work in a care home and some of the ladies in their late 80s and 90s never married because their father or mother or in two cases step mother just told them they were needed at home and not allowed to...)
Then again if you are handing over 18k I can see why you'd think it should be your party, with regards to including cousin Sue who means a lot to you even though your DD hasn't seen her since she was 7 and her DH to be has never met him, and your good friend whom you have spent so much time with in the last few years and who has heard so much about your kids even though she actually wouldn't be able to say with certainty just from looking at them which of your DDs is which...
Probably people should pay for their own weddings these days,as the "old" method of funding and "new" insistence of adults to make their own decisions are not necessarily compatible :o
Use the 18k for a round the world trip/ cruise... :o