All of your posts come across with a touch of the martyred / passive aggressive / drama queen.
As a PP said - you keep contradicting yourself! All of the "oh it doesn't matter that I gave them loads of money" shit, when it clear it does, to you.
Fair enough if you think a £30K house deposit means you should get 2 guests. I'm sure plenty of people agree. But please, you can't say you gave the deposit as a gift with no expectations, and then bang on about it in the context of these extra guests!
You have a husband, inlaws and two grown up daughters. why do you "need" someone to feel proud with? Won't your own husband do?
Perhaps your son doesn't like this couple? (my parents have no idea that I can't stand their best friends)
I think it would be lovely of your son to include them for you, but far from something you should be upset about not happening.
I have 10 young adults I've never met coming to my wedding - 10% of the list - because I want my adult stepchildren to have a great time. I'm paying for them all, and gladly. But if I got a whiff that step children expected it, I'd be very disappointed in them.