Actually, FIL knows MIL best. And whether they have separate or joint accounts, the one thing that is clear that it's not the OP and DH's money, nor their business.
True, but things like this often end badly with (in this case) parents possibly having a fight which effectively concludes their marriage or causes extreme financial hardship further down the road causing others to have to get involved whether that was their intention or not. When the time comes that MIL and/or FIL has to request 'bailout' money, then it does indeed become "their business".
Or MIL might be furious that her children knew about this fiasco and did nothing to stop it. She may see it as them contributing to the jeopardizing of her financial future when they could have prevented it from happening. If family members stop speaking to each other and harboring resentments, that also directly affects others besides MIL and FIL and again, when it does, then it becomes "their business".
And this would not be the first time tignduff and her husband had to pony up money for a party, as she posted about in No. 28.
I'm having a very hard time with any justification that there is a reason (outside of safety, maybe a cheating situation, or something that will bankrupt (catastrophic consequences)) that makes it ok for anyone to butt into someone else's financial situation and marriage. Yes this is an expensive party, per the OPs and maybe even FIL/MIL's standards. Maybe the party is even getting out of hand. But to decide that anyone would have a right above FIL to go behind his back and tattle to his wife, effectively ruining any surprise he has for her, because for some reason they know better than him how she will react is beyond me. This is their marriage. And it's their finances. If the OP is really so concerned that he's making a huge mistake, then they can bring it up with him (though I think that's overstepping too). But if he doesn't want to talk about it, or doesn't want to accept their warnings, then that's on him.
So, how ironic is it that the OP may justify going behind FIL's back and inserting herself into his business to avoid this impending divorce that a surprise party would may or may not result in, and cause an even bigger rift. Not only the potential to cause MIL and FIL to have an epic fight before they even get to their anniversary, but the even greater liklihood of hurting her and her DH's relationship
with one or both of his parents.
If they are going to fight, let them fight. If something like a credit card bill is going to push them to divorce after 45 years of dealing with these same issues (who hasn't after even just 2 years?), then they divorce. It's their relationship
. The OP may not like them to break up, but it's not her job to intercept all these possible fights to protect them against it. She's not "relationship
Woman", here to save the day before you even know there's a problem.
And, I said this before and I'll say it again. Just because SIL/BIL asked the OP for money before, doesn't mean that FIL is planning to or going to this time. By that logic, who's to say that the OP and her DH aren't planning to pull the same stunt themselves? Afterall, they are all part of the same family and that makes the history