Mother offers to pay $2000 for her son's wedding, and it was supposed to cover everything, until last minute they changed the party and expected the mother to pay more: 'I didn't agree to a 70-person party, and nobody asked me before they changed it'

If you decide what to do, then don't ask for more money.

If something is done the way you want it, with all the perks you chose, and without anyone else's input. Then I don't think you can expect someone else to pay for it. You are choosing everything, even the amount that will be spent; normally, not everyone will be willing to cover your expenses and dreams. If you get the offer from someone to pay for your wedding like this couple, you take it, thank them, and use it. You don't expect more money to do a bigger event just because you think that the person gifting you money owes it to you. Nobody owes you anything. If they want to help out financially for the wedding, it is out of the kindness of their heart. Not due to some kind of entitlement that makes you think you deserve more than you do. You are an adult capable of paying for your own things. If you get a gift, it is just that, not something you'd deserve to get forever. It is just a one-time gift. Accept it or decline it, but to expect even more than what they offered is insane, and it shows entitlement.  

This story made me think about those friends who you tell you want to invite them out to dinner just because, and then they change their normal order to the most expensive thing on the menu, even if they don't particularly like what they are ordering. They think that just because they aren't paying, they deserve to do whatever they want and not think about the person who offered to pay. Someone will come here and say that if you don't have the money to invite the food, then don't offer. And I agree, but it doesn't apply to ordering the most expensive thing on the menu just because you aren't paying. That is not just enjoying the offer your friend did. That is going too far and being an entitled person. You can expect them to not invite you to dinner ever again after all that.  

You aren't allowed to splurge on another person's money. They gift you what they want to gift you. Whether it's $5 or $5000, you have to be grateful and not expect more. Nobody is obliged to give you money. They gave it to you because they wanted to do so as a gift. It wasn't a payment or an obligation. So if you think you deserve more than what they gave you, then maybe you don´t deserve anything at all. So, in this case, the mother of the groom doesn't have to give them money. Maybe if they are so sure that $2000 will not be enough to host a nice enough wedding, then maybe they shouldn't be receiving anything to begin with. It's a gift, not some kind of obligatory payment that she has to make. I'm not sure if it's the best decision to contribute at all after they acted so entitled about it.