We're going through a weird money situation as well (didn't want to thread-hijack).
FI and I are
 planning a wedding we're capable of paying for ourselves. FIs parents 
have very generously offered to pay for the RD and a large portion of 
the reception, which was not necessary, but we're appreciative. 
My mom 
(BSC) had offered us a sizable amount, which I declined due to the imminent threat of crazy strings (kind of like silly string, if silly 
string was emotionally weighted and mind-fuckingly manipulative). 
Even
 though we didn't go into this process expecting any help, and we can 
completely afford to pay for our own wedding, I think FI is feeling a 
little resentful. He hasn't said it in so many words, but it seems like 
he thinks it's unfair that my family may be credited with hosting, when 
we've straight-out refused their money. I think he'd also prefer our 
bank accounts to shrink less. It's one thing to say in theory that we'll spend a certain amount on the wedding, but in reality it's painful to cut large checks out of hard-earned savings. We've had a few 'managing expectations' 
conversations, and he says that he gets it - that the money wouldn't be 
free. But, without having had extensive experiences with someone like my mom, I don't think he fully appreciates how much we would regret it down the road.
Beyond maintaining the stream of 'money is never free', does anyone have any suggestions for this one?
Edited for spelling. Eminent and imminent are very different words.